Curr Oncol, Vol. 21, pp. 294-304; doi: http://dx.doi.org/10.3747/co.21.2056
O R I G I N A L
A R T I C L E
Screening histories and contact with physicians as determinants of cervical cancer risk in Montreal, Quebec A.R. Spence PhD* A. Alobaid md/ P. Drouin md/ P. Goggin md/ L. Gilbert md/ D. Provencher md/ P. Tousignant md Pho/** J.A. Hanley phd/ and E.L. Franco DrPH*# ABSTRACT
Conclusions
Background
O u r findings provide evidence o f the n eed for an or g an ize d p o p u latio n -b ased screen in g pro g ram . T h ey also u n d ersco re the n eed for p ro v id er ed u catio n to prevent m issed o p p o rtu n itie s for cca screen in g w hen at-risk w om en seek m edical attention.
C erv ical ca n cer (cca) is largely a p reventable disease i f w o m en re ceiv e re g u la r scre e n in g , w h ich allow s for th e d e te c tio n an d tre a tm e n t o f p re in v a siv e le sio n s b e fo re th e y b e c o m e in v asiv e. H a v in g b e e n in a d e q u a te ly sc re e n e d is a co m m o n fin d in g am o n g w om en w ho develop cca. O u r p rim a ry objective w as to d e te rm in e th e P ap sc re e n in g h isto rie s o f w om en d iag n o sed w ith cc a in M ontreal, Q uebec. S eco n d ary o b jectiv es w ere to d e te rm in e the c h a ra c te ristic s o f w om en at g re a te st risk o f cc a and to c h a ra c te riz e the level o f p h y sician c o n ta c t th o se w om en h ad before d ev e lo p in g cca.
Methods T h e In v a siv e C e rv ic a l C a n c e r S tudy, a p o p u la tio n b a s e d c a s e —c o n tro l stu d y , c o n s is te d o f G re a te r M o n tre a l re s id e n ts d ia g n o s e d w ith h isto lo g ic a lly c o n firm e d c c a b e tw e e n 1998 a n d 2 0 0 4 . R e sp o n d e n ts to th e 2 0 0 3 C a n a d ia n C o m m u n ity H e a lth S u rv e y a n d a sam p le o f w o m en w ith o u t c c a o b ta in e d fro m Q u e b ec m ed ica l b illin g re c o rd s serv ed as c o n tro ls.
Results D u rin g th e p e rio d o f in te re st, 568 w o m en w e re d iag n o sed w ith cca. Im m ig ran ts an d w om en speak ing n eith er F rench nor E nglish w ere at g re atest risk o f cca. M ost o f the w om en in the case g roup h ad b ee n s c re e n e d at le a st o n ce d u rin g th e ir lifetim e (8 4 .8 % —90.4% ), but th ey w ere less lik ely to have b ee n screen ed w ith in 3 y ea rs o f diagnosis. H av in g receiv ed care from a fam ily physician or a m edical specialist o th er th an a g ynecologist w ithin the 5 years before d iag n o sis w as asso ciated w ith a g re ater risk o f cca developm ent.
KEY WORDS C erv ical cancer, P ap an ico lao u test, screen in g
1.
BACKGROUND
Invasive cerv ical ca n cer (cca) is the th ird m o st co m m on fem ale m alig n an cy w orldw ide, w ith th e g re a t est bu rd en being seen in developing c o u n trie s'. T he d isease is less co m m o n in the W estern w orld, w here g re a te r use o f the P ap an ico lao u (Pap) test, w hich allow s for early d e te c tio n o f p re in v a siv e c e rv ical lesio n s, an d ap p ro p ria te follow -up have re n d e re d cc a a largely p reventable disease. E fforts to prevent cc a have achieved g reat success in C anada: the in cidence o f cc a has d eclin ed to its cu rre n t rate o f 7.5 p er 100,0 0 0 2 from an estim ated 22 cases p er 100,000 p o p u latio n in 19703. N ev erth eless, about 1450 C an a d ian w om en are d iag n o sed w ith cca a n n u a lly 2. D esp ite the a v a ila b ility o f c e rv ic a l sc re e n in g in m ore developed c o u n trie s, an estim ated 54% o f w om en w ith cc a have eith er nev er b een screen ed or have no t b een screen e d freq u en tly enoug h before diagnosis4. E arlier studies that set out to estim ate fail ures in screening am ong w om en w ith c ca4 w ere often lim ited because m any had few subjects, w ere hospital o r clinic b ased , an d did not in terv iew subjects. W e audited Pap screen in g h isto ries o f all w om en diagnosed w ith cca w ho resided in M ontreal, Q uebec, to o btain insights ab o u t the h ealth care u tiliza tio n c h a rac te ristic s th at could have placed them at risk o f developing the disease. W e used su rv ey an d a d m in istra tiv e health care d ata as control sam p les to
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SPENCE et al.
m easu re co m p lian ce w ith screen in g an d physician v isits in the g en eral population.
2. METHODS 2.1 Study Setting T h e In v a s iv e C e rv ic a l C a n c e r S tu d y (ic c a s), a p o p u la tio n -b a se d c a s e -c o n tr o l in v estig atio n , w as c o n d u c te d in M o n tre a l a n d L av a l, Q u e b e c . P ap screen in g in Q u eb ec is o p p o rtu n istic ; no o rganized Pap screen in g p ro g ram is in place. D u rin g the study p e rio d , a n n u a l P ap s c re e n in g h a d b e e n re c o m m en d ed for 2 co n secu tiv e years fro m age 18 or afte r in itia tio n o f sex u al ac tiv ity ; sc re e n in g freq u en c y co uld th en be ex ten d ed to 3 years i f all sm ears w ere n o rm a l5’6. C a n a d a p ro v id e s fre e u n iv e rsa l h ea lth care to resid en ts. S ubsequently, p hysicians subm it m o n etary claim s to the governm ent for rem uneration o f serv ices p ro v id ed . T he Q uebec g o v ern m en t body resp o n sib le for p ay m en t to p hysicians is the R egie de l ’assu ra n ce m alad ie du Q uebec ( r a m q ).
2.2 Case Identification and Data Collection Methods T h e case g ro u p co n sisted o f w om en d iag n o sed w ith p rim a ry h isto lo g ically co n firm ed cca at a M ontreal or L aval hospital b etw e en 1998 and 2004 (Table i). T h e w o m en h ad b een resident in th o se regions for a m in im u m o f 5 y ears before an d at diagnosis. U sing the In tern a tio n a l C lassification o f D iseases, 9 th revi sion, co d es 180.0—180.9, cases w ere identified by the p ro v in cial tu m o u r re g istry and by m ed ical records d ep a rtm en ts at 18 hospitals th at review P ap sm ears and th at o ffer d iag n o stic and trea tm e n t serv ices for c c a in g re a te r M o n trea l. R e c o m m e n d a tio n s state th at screen in g can stop at age 70 if a w om an has h ad at least 2 satisfactory, cy to lo g ically n o rm al Pap sm ears in the p re ced in g 9 y ea rs and has n ev er had a b io p sy -co n firm e d p re c u rso r lesion5,6. N e v erth eless, inclusion o f w o m en into the case g roup w as not re stricted b y age, b ecau se fu lfillm e n t o f those crite ria co uld not be d eterm in ed w ith c e rtain ty based on data co llected d u rin g th e study. D ata collected included d ates an d re su lts o f Pap tests, d iag n o stic p ro ced u res, an d tre a tm e n ts for p rein v asiv e cervical lesions (in cluding nam es o f physicians p erfo rm in g the services, and n am es o f h o sp ital laboratories w here specim ens w ere ex am in ed ) and d em ographic ch a rac te ristic s o f th e stu d y subjects. U sin g a sp ec ia lly d esig n ed , p ilo t-te ste d form , tra in e d a b s tra c to rs in itia lly c o lle c te d d a ta fro m m ed ical ch a rts at th e hospital th at d iag n o sed each case. T h e in fo rm atio n from the ch a rts th en guided th e ab stra cto rs to o th er hospitals at w hich to review ch arts. A b o u t 14% o f ch a rts w ere rev iew ed at least tw ice. T he q u ality o f d ata collection w as assessed by d eterm in a tio n o f inter- and in tra-a b stracto r relia b ili ties at several p o in ts d u rin g the data collection phase.
H o sp ital cy to lo g y an d p a th o lo g y la b o ra to rie s provided re p o rts o f P ap tests and cca-related p ro c e dures. T elephone in terv iew s o f p atien ts in the case group (or th e ir proxies) w ere co n ducted by tra in e d in terv iew ers u sin g a stru c tu re d q u estio n n aire th at w as p ilot-tested on w om en w ho w ere sim ilar to the w om en in the case g roup and w ho had b een d iag n osed w ith cca in 1997. To o b tain a d escrip tio n o f all cases o f cca o c c u rrin g w ith in the tim e an d region o f interest, an abb rev iated version o f the q u estio n n aire (dem ographic inform ation only) w as ad m in iste red to sh o rt-term resid en ts o f M ontreal an d Laval w ho m et all o th er elig ib ility criteria. F am ily physicians and gynecologists com pleted a self-adm inistered questionnaire and provided copies o f laboratory reports for Pap tests and other cervixrelated procedures. Physician m edical billing records obtained from the r a m q consisted o f all m edical ser vices reim bursed for each w om an in the case group w ith in the 5 years before diagnosis, including the date o f each service and the m edical specialty o f the physician w ho perform ed the service. N o r a m q code specific to perform ance o f a Pap test exists; hence, m edical billing records could not be used to determ ine screening histories.
2.3 Auditing of Pap Screening History for the Case Group E ac h c a se -sp e c ific o b s e rv a tio n w in d o w c o n sis te d o f tw o p e rio d s , as d e p ic te d in F ig u re 1. T h e d ia g n o stic p e rio d w a s b o u n d e d b y th e d a te o f d ia g n o sis (th at is, d a te o f th e first p ro c e d u re p ro v id in g h isto lo g ic p r o o f o f cca) a n d th e d a te o f th e first c y to lo g ic a lly a b n o rm a l o r e q u iv o c a l P ap sm e a r w ith in 5 y e a rs p re c e d in g d ia g n o sis. T h a t P ap te s t w a s te rm e d th e “ tr ig g e r P a p ” b e c a u s e it i n i t i ated th e e n su in g c a sc a d e o f fo llo w -u p p ro c e d u re s le a d in g to th e c c a d ia g n o sis. To be c a te g o riz e d as th e trig g e r P ap, th e te s t h ad to b e th e o n ly c e rv ix re la te d p ro c e d u re p e rfo rm e d th a t sam e day. T h e p re -d ia g n o s tic p e rio d c o n s is te d o f th e tim e fro m th e d a te o f th e trig g e r P ap to th e b e g in n in g o f th e o b se rv a tio n w in d o w — th a t is, th e s ta rtin g d ate o f th e 5 y e a rs p re c e d in g th e d ia g n o sis d ate. To av o id c o n sid e rin g th e P ap te s ts th a t fo rm e d p a rt o f th e final w o rk -u p to w a rd th e c c a d ia g n o sis, th e d e te r m in a tio n o f P ap s c re e n in g h is to rie s w a s lim ite d to s c re e n in g th a t o c c u rre d d u rin g a n d p re c e d in g th e p re -d ia g n o s tic p e rio d . W om en w ere ca teg o rized as “ever sc re e n e d ” if th ey h ad a Pap te st classified as cy to lo g ically norm al d u rin g the p re -d iag n o stic p erio d o r i f they h ad Pap tests o f any resu lt before the p re -d iag n o stic p erio d (or both). T hey w ere categorized as “nev er screen e d ” i f there w as no evidence o f P ap screen in g w ith in or before the p re -d iag n o stic p erio d a n d i f the w om an (or h er proxy) said d u rin g the in terv iew th at she h ad never been screened d u rin g h er lifetim e. W om en w ho
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DETERMINANTS OF CERVICAL CANCER RISK
w ere classified as “ever screened” w ere fu rth e r cat egorized based on the tim e in terv al b etw een date o f diagnosis and either the last Pap test considered norm al ( if it o ccu rred d u rin g the p re-d iag n o stic table
i
Description of the case and control groups of the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004 Descriptor
Cases
Controls
Subject identification
Quebec Tumour Registry and medical records departments at hospitals
Subject inclusion criteria
Diagnosed with a primary, histologically confirmed cervical cancer at a Montreal or Laval hospital during 1998-2004 Resident in the region for a minimum of 5 years before and at diagnosis
Data sources
Abstraction of data from hospital medical charts Reports obtained from hospital cytology and pathology laboratories Telephone-based interviews of cases or proxies Self-administered questionnaire completed by family physicians and gynecologists Physician medical billing records from the ra m q (dates and procedure codes for all medical visits by each patient in the 5 years preceding the index date, including the medical specialty of the physician handling the visit)
cchs
p eriod) or the last Pap test o f any resu lt (if it o c cu rred before the p re-d iag n o stic period). Classification o f each wom an’s Pap screening his tory was based on at least one o f the following sources
Group 1
Group 2
Statistics Canada, 2003 cchs (cycle 2.1)
Physician medical billing records from the ram q
Female residents in Montreal Using each date of a histologic or Laval who participated in cervical cancer diagnosis (case) the 2003 cchs as an index date, the ra m q provided a random sample of women without cervical cancer who were individually matched (1:1) to the women with cervical cancer by age (within 5-year age groups) and region of residence (Montreal or Laval) Responses to the 2003
cchs
Physician medical billing records from the ra m q (dates and procedure codes for all medical visits by each control subject in the 5 years preceding the index date, including the medical specialty of the physician handling the visit)
= Canadian Community Health Survey; ra m q = Regie de l’assurance maladie du Quebec.
Pap tests of any result
-5
One or more cytologically normal Pap tests
D e fin itio n o f Ever Screened
Time prior to diagnosis (years)
A First abnormal Pap test ('Trigger Pap’)
Date of diagnosis
Diagnostic Period
Pre-Diagnostic Period
D e fin itio n
No Pap tests founda
«■
*■
of N ever Screened
1 Periods o f observation and operational definitions o f “ever screened” and “never screened.” a In addition, the woman in the case group (or her proxy) must have completed the subject questionnaire and must have stated that she was never screened.
f ig u r e
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SPENCE et al.
(listed in d eclin in g order o f reliability): laboratory rep o rt (obtained d irectly from a hospital laboratory, found in the hospital chart, or sent to us by a physi cian) and a secondary source (physician questionnaire, an n o tatio n w ith in the m edical chart, or case or proxy interview ). B ased on the sources o f data available for a given w om an and the concordance o f results betw een them , the term s “definite,” “probable,” and “possible” w ere u sed to indicate the degree o f confidence attained in the classification o f each w om an’s screening history, w ith th e first and last term s indicating the m o st and least d eg rees o f con fidence respectively. H isto ries deem ed as “definite” w ere u sed in the analyses.
(cis) for asso ciatio n s b etw e en c h a rac te ristic s o f the stu d y subjects an d c c a (overall an d by c a n c e r stage). T he o rs w ere ad ju sted for age (±5 years) at d iagno sis for the case g roup and at tim e o f in terv iew for control group 1. D eg ree o f invasion w as classified as lo cal ized (In te rn a tio n a l F ed eratio n o f G y n e co lo g y and O b stetrics stages i a I , ia 2 , i b ) , reg io n al (stages i i a , i i b , i i i a , i i i b ) , o r d istan t (stage iv)8. F or m o d ellin g , the first tw o categories w ere g ro u p e d an d co m p ared w ith the th ird category. S creening h isto ry w as categ o rized in th ree ways: • •
2.4 Control Identification and Data Collection Methods • C o n tro l su b jects w ere d eriv e d fro m tw o so u rc es, as n o ted in Table i. W om en re sid in g in M ontreal or L aval w ho p a rtic ip a te d in the 2003 (cycle 2.1) C a n ad ian C o m m u n ity H ealth S urvey ( c ch s ) co m p rised one co n tro l g ro u p (control g roup 1). T he c ch s is a g o v e rn m e n t-in itia te d c ro ss-se c tio n a l su rv e y th a t o b tain s health in fo rm atio n ab o u t C an ad ia n s7. T hese control subjects w ere not interview ed by o ur research staff; in stead , th eir responses to c ch s questions about d em o g ra p h ics a n d P ap sc re e n in g u tiliz a tio n w ere co m p ared w ith the sam e d ata for the w om en in the case g roup w ho resp o nded to the ic c a s questionnaire. It should be n o ted th at the p e rtin e n t q uestions in the c ch s and the ic c a s h ad essen tially the sam e w ording; any d iffe ren c es w ere in consequential. A second co n tro l g roup (control g roup 2) w as d eriv ed fro m d ata held by the r a m q . U sing the date o f h istolo g ic d iag n o sis w ith cc a for each w o m an in th e case g ro u p as th e index date, the r a m q pro v id ed a ra n d o m sam ple o f w om en w ith o u t cc a w ho w ere in d iv id u ally m atch ed (1:1) to cc a cases b y age (w ithin 5-year age groups) an d region o f residence (M ontreal o r L aval). T h e r a m q pro v id ed the d ates an d p ro c e d u re co d es o f all m ed ica l serv ices th at the control subjects received in the 5 y ears before the index date, in clu d in g th e m ed ical sp ecialty o f th e p h y sician w ho p ro v id ed each serv ice. C o n tacts w ith fa m ily physi cians, gynecologists, and o ther m edical specialists for the control subjects w ere then counted and com pared w ith the m ed ical co n tac t profiles before diag n o sis o f the w om en in the cca case group. E thics approval w as o b tain ed fro m p e rtin e n t in stitu tio n s and hospitals, and signed inform ed consent w as o b tain ed from all subjects. W om en in the case g ro u p or th e ir p ro x ies w ere co n tacted only i f physi cian s p ro v id ed sig n ed perm ission. T he C om m ission d ’acces a l’info rm atio n approved receipt o f d ata from th e Q u eb ec tu m o u r re g istry and r a m q . 2.5 Statistical Analysis U n c o n d itio n al logistic reg ressio n w as u se d to esti m ate o d d s ra tio s ( o r s ) and 95% confidence in terv als
Lifetime screening history (never, ever, unclassified) T im e since last P ap te st (80 Years Age at diagnosis (years) Median Mean Range Presence of symptomsb [n (%)] Yes No Unknownc Symptom type, when present Vaginal discharge Bleeding Vaginal, intermenstrual Vaginal, postmenopausal Vaginal, postcoital Menstrual, heavy or prolonged Abnormal, type unspecified Loss of appetite Weight loss Fatigue Paine Other symptoms Disease stage [n (%)] ia I ia 2
IB II III IV
Unknown Tumour histology [n (%)] Squamous cell Adenocarcinoma Adenosquamous Other less common types Unknown
Valuea 23 (4.0) 91 (16.0) 137 (24.1) 103(18.1) 76 (13.4) 86 (15.1) 52 (9.2) 52 55 22-94 399 (70.2) 51 (9.0) 118(20.8) 69 (17.3) 101 (25.3) 200 (50.1) 68 (17.0) 12 (3.0) 5 (1.3) 15 (3.8) 64 (16.0) 18 (4.5) 95 (23.8) 45(11.3) 89 (15.7) 31 (5.5) 173 (30.5) 113 (19.9) 105 (18.5) 42 (7.4) 15 (2.6) 410 (72.2) 123 (21.7) 16 (2.8) 14 (2.5) 5 (0.9)
a Percentages may not add up to 100 because of rounding. b Including abnormal vaginal discharge, intermenstrual vaginal bleeding, postmenopausal vaginal bleeding, heavy or prolonged menses, postcoital vaginal bleeding, loss of appetite, weight loss, fatigue, pain (pelvic, abdominal, back, or leg), and other less common symptoms. The “other” category includes anemia, dyspareunia, dysuria, hematuria, rectal bleeding, urinary or renal tract problems, ascites, and vesicovaginal fistula. c Data indicating the presence or absence of a particular charac teristic were not found in the medical chart. d Subject could have experienced more than 1 symptom («=399). e Pelvic, abdominal, back, leg, or unspecified location.
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Associations between demographic characteristics of the study subjects and cervical cancer in the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004
table hi
Characteristic
Place of birth Canada Other If not Canadian-born, time in Canada 0-9 Years >10 Years Marital status Married Common-law Widowed, separated or divorced Single Language of conversation English and French'1 English, not French'* French, not English'1 Neither English nor French Employment status Employed Unemployed, homemaker Student Retired Highest level of education Less than secondary graduation Secondary graduation Some postsecondary education Postsecondary degree or diploma Smoking status Never-smoker Current smoker Former smoker Childbirth in preceding 5 years No Yes Had a regular doctor No Yes Chronic condition No Yes
Study group [ n
(% )]
95% c i c
or
Casesa
Controlsb
256 (71.1) 104 (28.9)
1442 (77.4) 421 (22.6)
Reference 1.4 1.1 to 1.8
22 (23.9) 70 (76.1)
109 (26.4) 304 (73.6)
1.5
126 (34.9) 61 (16.9) 107 (29.6) 67 (18.6)
662 (33.5) 215 (10.9) 587 (29.7) 513 (25.9)
Reference 1.6 1.1 to 2.3 1.1 0.8 to 1.4 0.9 0.6 to 1.2
136 (37.8) 37 (10.3) 173 (48.1) 14 (3.9)
1034 (55.4) 153 (8.2) 653 (35.0) 28 (1.5)
2.0 2.1 4.5
206 (57.5) 67 (18.7) 8 (2.2) 77 (21.5)
940 (58.1) 284(17.5) 41 (2.5) 354 (21.9)
Reference 1.0 0.7 to 1.4 1.7 0.8 to 4.0 0.4 0.3 to 0.7
107 (30.9) 72 (20.8) 68 (19.4) 99 (28.6)
498 (25.5) 251 (12.9) 105 (5.4) 1096 (56.2)
0.9 2.4 0.3
131(40.1) 123 (37.6) 73 (22.3)
676 (34.2) 537 (27.2) 763 (38.6)
1.1 0.4
Reference 0.8 to 1.5 0.3 to 0.6
294 (89.4) 35 (10.6)
887 (82.7) 186 (17.3)
1.3
Reference 0.9 to 2.1
95 (29.7) 225 (70.3)
408 (20.6) 1574 (79.4)
1.9 1.4 to 2.5 Reference
246 (75.5) 80 (24.5)
448 (22.6) 1534 (77.4)
13.4 10.0 to 18.0 Reference
0.8 to 2.9 Reference
Reference 1.4 to 3.1 1.6 to 2.7 2.3 to 9.1
Reference 0.6 to 1.3 1.6 to 3.6 0.2 to 0.4
a Women with invasive cervical cancer for whom data from the subject interview were available. These women might or might not have lived in Montreal or Laval for at least 5 years («=362). For some questions, numbers might not total to 362 because of nonresponses. The smoking status, childbirth, regular doctor, and chronic condition analyses include only women who resided in Montreal or Laval for a minimum of 5 years before diagnosis because only those women completed the long version of the questionnaire («=330). b Women living in Montreal or Laval who responded to Statistics Canada’s 2003 Canadian Community Health Survey. c Models were adjusted for age (20-24, 25-29, 30-34, ..., >80 years) at diagnosis (cervical cancer patients) or at time of Canadian Community Health Survey completion (controls). d Might also speak another language. or = odds ratio; ci = confidence interval.
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DETERMINANTS OF CERVICAL CANCER RISK
had a statistically significantly greater risk o f cca. This increased cca risk w as present up to 9 years a fte r im m ig ra tio n to C anada. S p eak in g neith er E nglish nor French, having som e p o stseco n d ary education, not having a regular doctor, and not hav ing a chronic condition were all associated w ith a statistically significant greater risk o f cca. There was also a statistically nonsignificant indication that the risk o f advanced cca was greater in m ore recent im m igrants and in those w ithout a regular doctor (data not shown). For the study group, Table iv shows Pap screen ing histories and their associations w ith cca risk. M ost w om en in the case group had been screened at least once in their lifetim e, w ith the frequency v ary in g from 84.8% to 90.4% depending on the
analysis. A n e stim a te d 30.9% —56.8% had b een screened w ith in 3 years o f diagnosis. W hen all sources o f data w ere used to determ ine screening histories o f the w om en in the case group, a statisti cally significant increased cca risk w as associated w ith b e in g ev er-screen ed co m p ared w ith b ein g never-screened. W hen the case group was restricted to w om en whose screening categorization w as clas sified as “definite,” the point estim ate w as lower and no longer statistically significant, but it rem ained above 1. W hen screening histories in the case group w ere lim ited to data obtained solely from the iccas questionnaire, being ever-screened appeared to be associated w ith a low er cca risk, although the result ju st bordered on significance. M oreover, the longer the tim e interval since the last Pap test, the greater
iv Associations between screening history (Pap tests) and cervical cancer in the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004
table
Pap screening history
Screening variable Based on all sources o f data Casesa /n (%>)]
Controls'0 [n (%>)]
Adjusted0 or
Based on all sources o f data and screening history reliability deemed “definite ”
95% c i
Adjusted0
Casesa [n (%)] OR
Screening classification Never Ever Not classified11 Time since last screen for the ever-screened6 80 years). d Based on available data, the screening histories of 161 women could not be classified as “ever” or “never” screened. However, it was determined that they had not been screened within the 5 years preceding their diagnosis with cervical cancer. e Refers to women who were “ever” screened in the past. f “Inadequate” includes women in the case group who were never screened, who were screened within 5 years of diagnosis (but not within 3 years), who were screened more than 5 years before diagnosis, and for whom ever or never screening could not be determined, but for whom no screening in the 5 years preceding diagnosis could be determined. Subjects categorized as “ever screened,” but whose time since the last normal screen could not be defined were omitted («=6). For Canadian Community Health Survey respondents (control group 1), “inadequate” refers to women never screened and to those whose last screen occurred between 3 and 5 years or 5 or more years in the past. “Adequate” refers to patients screened within 3 years of their diagnosis. Adequacy was defined based on prevailing clinical practice guidelines. or = odds ratio; ci = confidence interval; na = not applicable. I C urrent O ncology — V olume 21, N umber 6, December 2014 I Copyright © 2014 Multimed Inc. Following publication in Current Oncology, the full text of each article is available immediately and archived in PubMed Central (PMC).
SPENCE et al.
th e risk o f c c a, a fin d in g th a t w as e sp e cially ev id en t w h en th e ca se g ro u p w as lim ite d to w om en w hose screen in g cate g o riza tio n w as deem ed “definite.” A ll th re e an a ly se s fo u n d th a t an in a d e q u a te sc re e n in g h is to ry w as asso c ia te d w ith a sta tistic a lly sig n ifi ca n tly g re a te r ris k o f cca. S im ilarly, n ev e r b ein g screen e d o r th e p assa g e o f 5 or m ore y ea rs since last sc re e n in g w ere a sso c ia te d w ith an in c re a se d risk o f b ein g d ia g n o se d w ith re g io n a l o r d ista n t c c a ra th e r th a n lo c a liz e d c a n c e r (data n o t show n). A s T able v show s, h a v in g receiv ed care from a g y n ec o lo g ist w as asso ciated w ith a low er risk o f d ev eloping cca, even a fte r co n tro llin g for visits to o th er p hysicians. In co n trast, a g re a te r risk o f cca w as observed i f care w as received from other m edical sp ecialists o r fro m fam ily physicians.
4.
DISCUSSION
O u r stu d y u n d e rsc o re s the im p o rta n c e o f re g u la r screening for the prevention and early diagnosis o f cca. M ost w om en in the case group had undergone a Pap test at least once in th eir lifetim e (85% -90% ). However, depending on the sources o f data used for de term in in g screening, 4 3 % -6 9 % o f those w om en w ere not screened w ith in 3 years o f diagnosis, and overall, an estim ated 53% —'74% had an inadequate screening history. T hose findings em phasize the failings o f o p p o rtu n istic Pap screening and h ighlight the need for screening w ith in the context o f an organized program
table
v
that has the m eans to invite w om en population-w ide to screening and to recall w om en for screening at ap propriate intervals. C o m p a re d w ith C a n a d ia n -b o rn w o m e n , im m ig ra n ts have a h ig h e r c c a risk , w h ich m ig h t be attrib u te d to p o o re r use o f sc re e n in g 9-14. C u ltu ral v a lu e s, b eliefs ab o u t se x u a l b eh a v io u r, la n g u a g e b arriers, fatalism , ac cu ltu ratio n , and lack o f k n o w l edge about cc a influence the u se o f Pap screen in g by im m ig ra n ts15-18. T he cca risk am ong im m ig ra n ts a p p e a rs to b e lo w er w ith len g th o f tim e liv ed in C an ad a , w hich m ig h t be a ttrib u ta b le to a g re a te r likelihood o f screen in g use in long-term im m ig ra n ts th an in re cen t im m ig ra n ts9’19,20. L an g u ag e b a rrie rs 10 and low er edu catio n level10,12,21 are asso ciated w ith g re a te r risk o f cca, likely b ec au se o f p o o r u se o f Pap sc re e n in g 9,10,20,22,23. T he stu d y re su lts also echo e a rlier fin d in g s9,10,20 in h ig h lig h tin g the im p o rtan ce to ap p ro p riate screen in g o f h av in g a re g u la r doctor. R eceipt o f care from a gynecologist, independ en t o f o th er physicians, w as asso ciated w ith a low er risk o f cca. C o m p ared w ith fam ily physicians, g y n e c o lo g ists are m ore likely to p erfo rm Pap te sts24,25, and w om en w ho w ish to have Pap tests p re fere n tia lly go to g y n eco lo g ists in stead o f fam ily phy sician s to be screened24,26. W e speculate that, because slightly less co n tact w ith gynecologists w as seen in w om en in the case group th a n in the control group, th e w om en in the case g roup w ere less likely to be screen ed and w ere, as a result, at g re a te r risk o f cca.
Associations between physician visits and cervical cancer in the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004 Practitioner type
Family physician 0 Visits 1 to 2 Visits 3 to 4 Visits >4 Visits Gynecologist 0 Visits 1 to 2 Visits 3 to 4 Visits >4 Visits Medical specialist other than gynecologist 0 Visits 1 to 2 Visits 3 to 4 Visits >4 Visits
Study group
or
95% ci
Adjustedb
Cases a [n (%)]
Controls [n (%)]
54 (9.6) 65(11.6) 55 (9.8) 388 (69.0)
146 (26.0) 53 (9.4) 49 (8.7) 314 (55.9)
Reference 4.8 2.7 to 8.4 4.4 2.4 to 7.9 5.2 3.3 to 8.2
Reference 3.6 2.0 to 6.6 3.4 1.8 to 6.6 4.3 2.4 to 7.6
355 (63.2) 110(19.6) 38 (6.8) 59 (10.5)
345 (61.4) 75 (13.4) 58 (10.3) 84 (15.0)
Reference 1.4 1.0 to 1.9 0.6 0.4 to 0.9 0.7 0.5 to 1.0
Reference 0.9 0.6 to 1.3 0.4 0.2 to 0.7 0.5 0.3 to 0.7
86 (15.3) 110(19.6) 65 (11.6) 301 (53.6)
172 (30.6) 67(11.9) 47 (8.4) 276 (49.1)
Reference 4.1 2.6 to 6.4 3.6 2.2 to 5.9 2.8 1.9 to 4.0
Reference 2.4 1.4 to 4.0 2.0 1.1 to 3.5 1.7 1.0 to 2.8
or
95% c i
a Of 568 patients who met the study inclusion criteria, 6 did not have a ra m q number. Matched controls were not obtained for the latter 6 patients, thus leaving 562 cases and 562 controls for analysis. b Each model was adjusted for the number of visits to other physician types, using the 0, 1-2, 3-4, >4 categories. or = odds ratio; ci = confidence interval. ______________________________________________________C urrent O ncology — V olume 21, N umber 6, D ecember 2014 Copyright © 2014 Multimed Inc. Following publication in Current Oncology, the full text of each article is available immediately and archived in PubMed Central (PMC).
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H av in g h ad sp ec ia list v isits w as asso ciated w ith a n in c re a s e d risk o f cca. C o m p ared w ith w om en n o t h a v in g c h ro n ic c o n d itio n s, w o m en w ith such co n d itio n s u n d erg o an y ty p e o f screen in g less often, esp e cially i f p hy sician s believe th at th o se w om en h av e a sh o rten ed lifesp an 27’28. T herefore, if, before d iag n o sis, ch ro n ic m orbidities th at re q u ire d care by sp ecialists w ere m o re p re v alen t in the case group th a n in th e co n trol group, it is plausible to assum e th at w o m en in th e case g roup w ould be less likely to receiv e P ap screen in g b ecau se o f the em phasis the specialist m ight have placed on properly investigating an d tre a tin g th e ch ro n ic condition. A low er o p p o rtu n ity to screen could co n seq u en tly have co n trib u ted to an in cre ased risk o f b ein g d iag n o sed w ith cca. A lth o u g h th is exp lan atio n is plausible, it m ig h t not a c tu a lly b e ap p licab le to o u r c o h o rt, b ec au se o u r stu d y fo u n d th at w om en in the case g roup re p o rted ch ro n ic d isease s less freq u en tly th a n did w om en in th e co n tro l group. H ow ever, th at fin d in g w as based on a su b g ro u p o f the case g roup w ho resp o n d ed to th e icca s q u e s tio n n a ire . T h o se w o m e n te n d e d to b e y o u n g er an d w ere p erh ap s less lik ely th a n the w o m en w ho did no t p artic ip a te in the su rv ey to have a ch ro n ic disease.
5.
STUDY LIMITATIONS AND STRENGTHS
L ack o f d ata p rev en ted a d e te rm in a tio n o f the life tim e screen in g h isto ries o f 161 w om en in the case g ro u p , w h ic h c o u ld u ltim a te ly h av e re s u lte d in o v erestim a tio n o f the p ro p o rtio n o f cases considered “ev er screen ed .” W om en in the case g roup w ith an u n classified h isto ry w ere d em o g ra p h ically sim ilar to w om en w ho ten d ed to have a p o o r Pap screen in g h isto ry (d ata n o t show n); hence, w e believe th at the w o m en w ith an u nclassified h isto ry w ere m o st likely to have b een n ever-screened. F urther, to be classified as n ev er-screen ed , w om en in the case group or th e ir p ro x ies m u st have re sp o n d ed to the iccas q u estio n n aire b y say in g th at th ey h a d n ever b een screened. W om en in the case g roup w ith unclassified screening h isto ries w ere less likely th an those w hose screen in g h isto ries w ere classified to have p artic ip a te d in the in terv iew (21.7% an d 72.5% respectively). H ence, al th o u g h w e did not find any evidence o f P ap screening befo re d iag n o sis, the 161 w om en in the case group co u ld n o t have b ee n classified as nev er-screen ed i f no in terv iew to o k place. B e c a u se m u ltip le d a ta so u rc e s w ere u se d for th e case h isto rie s, d iffe ren tial m isclassificatio n o f s c re e n in g h is to rie s m ig h t h av e a ffe c te d th e P ap s c re e n in g —c c a a sso c ia tio n s. W h e n d a ta fro m all so u rces w ere u sed to classify u se o f screen in g by w o m en in th e case group, the ten d en c y to ca te g o riz e th o se w o m en as ever-screened a p p e are d to be a g re a te r th a n it w as for w om en in the control group, w h ich re su lted in the o dds ratio b ein g g re a te r th an 1. T h at o b serv atio n m ig h t be attrib u tab le to the m ore
ex h au stiv e search for d ata and the v ario u s co n tex ts in w h ich d ata collection o c c u rre d for the case group. In co n trast, screen in g h isto ries in the contro l g roup w ere b ase d solely on re sp o n se s to the c c h s q u es tio n “H ave you ever h ad a P ap te st? ” T he o d d s ratio d eclin ed slightly in the an aly ses w h en the screen in g h isto ries u sed for the case g roup w ere th o se d eem ed to be “definite,” w hich is pro b ab ly reflective o f the g re a te r o b jectiv ity o f lab o ra to ry re p o rts co m p ared w ith o th er d ata sources. L ikew ise, the asso ciatio n b etw e en tim e since the last P ap test an d cca, w h en b ase d on all sources o f d ata, m ig h t also h av e b een affected by d ifferen tial m isclassificatio n b ec au se o f the m ultiple sources o f d ata for the case group. S ocial d e sira b ility bias a n d te le sc o p in g co uld have led subjects to re p o rt th eir last Pap test as o ccur rin g m ore recen tly th a n it a c tu a lly h ad , re su ltin g in an underestim ation o f tim e since the last Pap test29-31. Such b iases w ould have m o st affected the an aly ses b ase d on the iccas q u estio n n aire and the c c h s . T h e iccas q u estio n n aire re sp o n se ra te (64.8% ) m ig h t be a lim itatio n . H ow ever, th at ra te is h ig h er th an the rates in m an y sim ilar stu d ies th at in clu d ed cca c a ses32-35, an d although som e w om en in th e case g ro u p did no t re sp o n d to th e iccas q u estio n n aire , screen in g h isto ries could still be o btained fro m o th er d ata sources. O th er lim itatio n s in clu d ed th e ro u tin e d iscard in g b y physicians o f m edical files a fte r 5 years o f dorm ancy and the p o o r organization, m issing lab o ra to ry re p o rts, an d illegible h a n d w ritin g th at o ften c h a ra c te riz e d h ospital m edical charts. A lso , som e lab o rato ries re fu se d to provide re p o rts to o u r study, and o f th o se th at did, m an y did no t have co m p u ter ized system s and h ad m issin g records. S tudy stren g th s include a large stu d y p o p u latio n w ith com plete case asc ertain m en t, an extensive audit p ro cess for d ata retriev al (m ultiple sources o f d ata accessed), an d atten tio n to d ata q u ality th ro u g h s ta ff tra in in g an d co n tin u o u s m o n ito rin g o f d ata co llec tion. A lth o u g h technologies for cc a prevention m ig h t change in fu tu re, the im plications o f o u r stu d y w ould still be applicable.
6. CONCLUSIONS A g re ater cc a risk w as asso ciated w ith a p erio d o f 3 or m ore years since the last P ap test (com pared w ith screen in g in the p re ced in g 3 years). Im m ig ran t w om en, less ed u cated w om en, an d w o m en w ith la n g u ag e b a rrie rs w ere at g re a te st risk o f cca, as w ere w om en w ho receiv ed care fro m m edical sp ecialists o th er th a n g y n eco lo g ists an d fro m fam ily p hysicians in the 5 years p re ced in g diag n o sis (case group) or c c h s in terv iew (control group 1). O u r findings un d er score the im p o rtan ce o f provider education to prevent m isse d o p p o rtu n itie s for c c a screen in g w h en at-risk w o m en seek m edical atten tio n an d pro v id e fu rth e r evidence o f the n eed for an o rg a n iz ed p o p u latio n b ased screen in g program .
I C urrent O ncology — V olume 21, N umber 6, D ecember 2014 | Copyright © 2014 Multimed Inc. Following publication in Current Oncology, the full text of each article is available immediately and archived in PubMed Central (PMC).
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T he p rev en tio n o f invasive cc a re q u ires not only ad o p tio n o f th e P ap test, but also ap p ro p riate refer ral and trea tm e n t o f cerv ical in traep ith elial lesions b efo re th ey p ro g re ss to invasion. A n au d it o f the a p p ro p riaten ess o f such d o w n stre am p ro c esses o f care is w a rra n te d in the fu tu re, p a rtic u la rly as new screen in g tech n o lo g ies— for exam ple, testin g for h u m an p ap illo m a v iru s— b eco m e p a rt o f the stan d ard o f care.
7. ACKNOWLEDGMENTS T h e au th o rs ack n o w ledge and th a n k the follow ing p eo p le for th e ir in v aluable co n trib u tio n s to the su c cessfu l ex ecu tio n an d com pletion o f the iccas study: Dr. A lex F erenczy, Dr. M a rtin D aw es, Dr. G erald S tan im ir, Dr. P a rv iz G h a d iria n , Dr. F rancois L eh m an n , Dr. F lav ia D a Silva, M s. C laude R ich ard , and th e m an y p ath o lo g ists an d m edical reco rd s te c h n i cians at th e G re ater M o n treal an d L aval hospitals. A m o st h e a rtfelt th ank-you is also ex tended to the stu d y subjects an d th eir n ex t o f k in w ho p artic ip a te d in o u r study. T h is stu d y w as su p p o rte d fin an c ially th ro u g h g ra n ts from th e C an ad ian In stitu te s o f H ealth R e search (IH S-61108, M O P -64454, an d C RN 83320).
8. CONFLICT OF INTEREST DISCLOSURES E L F has no co n flicts o f in tere st w ith re sp e c t to the c o n te n t an d m essag e o f th e p re se n t w o rk , b u t he re p o rts h av in g serv ed as o ccasional p aid co n su ltan t to co m p an ies involved w ith h p v v ac cin atio n (M erck, G la x o S m ith K lin e ) a n d c e rv ic a l c a n c e r sc re e n in g (R oche, BD, Q iagen, G en-Probe). H is in stitu tio n has receiv ed th re e g ra n ts from M erck in p artia l su p p o rt o f research th at he initiated. A A declares no conflicts o f in tere st w ith re sp ect to the co n ten t an d m essage o f th e p re sen t w ork, but his in stitu tio n has received a g ra n t from G lax o S m ith K lin e in su p p o rt o f o th er u n re la ted research . N o o th er authors h ad financial co n flicts o f in tere st to declare.
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C orrespondence to: A ndrea Spence, D ivision o f C ancer Epidemiology, 546 Pine Avenue W est, M on treal, Quebec H2W 1S6. E -m ail: andrea.spence@ m ail.m cgill.ca *
Division o f C ancer Epidemiology, M cG ill U ni versity, M ontreal, QC. t D epartm ent o f O bstetrics and Gynecology, King K h a le d U n iv e rsity H o sp ita l, R iy a d h , Saudi A rabia. J Division o f Gynecologic Oncology, Centre hospitalier de FU niversite de M ontreal, M ontreal, QC. § Institut national de sante publique du Quebec, M ontreal, QC. II D epartm ent o f O bstetrics and Gynecology, M c G ill U niversity Health Centre, M ontreal, QC. # D epartm ent o f Epidemiology, Biostatistics, and O ccupational Health, M cG ill University, M on treal, QC. ** D irection de sante publique de l’A gence de la sante et des services sociaux de M ontreal, M on treal, QC.
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O R I G I N A L
A R T I C L E
Screening histories and contact with physicians as determinants of cervical cancer risk in Montreal, Quebec A.R. Spence PhD* A. Alobaid md/ P. Drouin md/ P. Goggin md/ L. Gilbert md/ D. Provencher md/ P. Tousignant md Pho/** J.A. Hanley phd/ and E.L. Franco DrPH*# ABSTRACT
Conclusions
Background
O u r findings provide evidence o f the n eed for an or g an ize d p o p u latio n -b ased screen in g pro g ram . T h ey also u n d ersco re the n eed for p ro v id er ed u catio n to prevent m issed o p p o rtu n itie s for cca screen in g w hen at-risk w om en seek m edical attention.
C erv ical ca n cer (cca) is largely a p reventable disease i f w o m en re ceiv e re g u la r scre e n in g , w h ich allow s for th e d e te c tio n an d tre a tm e n t o f p re in v a siv e le sio n s b e fo re th e y b e c o m e in v asiv e. H a v in g b e e n in a d e q u a te ly sc re e n e d is a co m m o n fin d in g am o n g w om en w ho develop cca. O u r p rim a ry objective w as to d e te rm in e th e P ap sc re e n in g h isto rie s o f w om en d iag n o sed w ith cc a in M ontreal, Q uebec. S eco n d ary o b jectiv es w ere to d e te rm in e the c h a ra c te ristic s o f w om en at g re a te st risk o f cc a and to c h a ra c te riz e the level o f p h y sician c o n ta c t th o se w om en h ad before d ev e lo p in g cca.
Methods T h e In v a siv e C e rv ic a l C a n c e r S tudy, a p o p u la tio n b a s e d c a s e —c o n tro l stu d y , c o n s is te d o f G re a te r M o n tre a l re s id e n ts d ia g n o s e d w ith h isto lo g ic a lly c o n firm e d c c a b e tw e e n 1998 a n d 2 0 0 4 . R e sp o n d e n ts to th e 2 0 0 3 C a n a d ia n C o m m u n ity H e a lth S u rv e y a n d a sam p le o f w o m en w ith o u t c c a o b ta in e d fro m Q u e b ec m ed ica l b illin g re c o rd s serv ed as c o n tro ls.
Results D u rin g th e p e rio d o f in te re st, 568 w o m en w e re d iag n o sed w ith cca. Im m ig ran ts an d w om en speak ing n eith er F rench nor E nglish w ere at g re atest risk o f cca. M ost o f the w om en in the case g roup h ad b ee n s c re e n e d at le a st o n ce d u rin g th e ir lifetim e (8 4 .8 % —90.4% ), but th ey w ere less lik ely to have b ee n screen ed w ith in 3 y ea rs o f diagnosis. H av in g receiv ed care from a fam ily physician or a m edical specialist o th er th an a g ynecologist w ithin the 5 years before d iag n o sis w as asso ciated w ith a g re ater risk o f cca developm ent.
KEY WORDS C erv ical cancer, P ap an ico lao u test, screen in g
1.
BACKGROUND
Invasive cerv ical ca n cer (cca) is the th ird m o st co m m on fem ale m alig n an cy w orldw ide, w ith th e g re a t est bu rd en being seen in developing c o u n trie s'. T he d isease is less co m m o n in the W estern w orld, w here g re a te r use o f the P ap an ico lao u (Pap) test, w hich allow s for early d e te c tio n o f p re in v a siv e c e rv ical lesio n s, an d ap p ro p ria te follow -up have re n d e re d cc a a largely p reventable disease. E fforts to prevent cc a have achieved g reat success in C anada: the in cidence o f cc a has d eclin ed to its cu rre n t rate o f 7.5 p er 100,0 0 0 2 from an estim ated 22 cases p er 100,000 p o p u latio n in 19703. N ev erth eless, about 1450 C an a d ian w om en are d iag n o sed w ith cca a n n u a lly 2. D esp ite the a v a ila b ility o f c e rv ic a l sc re e n in g in m ore developed c o u n trie s, an estim ated 54% o f w om en w ith cc a have eith er nev er b een screen ed or have no t b een screen e d freq u en tly enoug h before diagnosis4. E arlier studies that set out to estim ate fail ures in screening am ong w om en w ith c ca4 w ere often lim ited because m any had few subjects, w ere hospital o r clinic b ased , an d did not in terv iew subjects. W e audited Pap screen in g h isto ries o f all w om en diagnosed w ith cca w ho resided in M ontreal, Q uebec, to o btain insights ab o u t the h ealth care u tiliza tio n c h a rac te ristic s th at could have placed them at risk o f developing the disease. W e used su rv ey an d a d m in istra tiv e health care d ata as control sam p les to
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SPENCE et al.
m easu re co m p lian ce w ith screen in g an d physician v isits in the g en eral population.
2. METHODS 2.1 Study Setting T h e In v a s iv e C e rv ic a l C a n c e r S tu d y (ic c a s), a p o p u la tio n -b a se d c a s e -c o n tr o l in v estig atio n , w as c o n d u c te d in M o n tre a l a n d L av a l, Q u e b e c . P ap screen in g in Q u eb ec is o p p o rtu n istic ; no o rganized Pap screen in g p ro g ram is in place. D u rin g the study p e rio d , a n n u a l P ap s c re e n in g h a d b e e n re c o m m en d ed for 2 co n secu tiv e years fro m age 18 or afte r in itia tio n o f sex u al ac tiv ity ; sc re e n in g freq u en c y co uld th en be ex ten d ed to 3 years i f all sm ears w ere n o rm a l5’6. C a n a d a p ro v id e s fre e u n iv e rsa l h ea lth care to resid en ts. S ubsequently, p hysicians subm it m o n etary claim s to the governm ent for rem uneration o f serv ices p ro v id ed . T he Q uebec g o v ern m en t body resp o n sib le for p ay m en t to p hysicians is the R egie de l ’assu ra n ce m alad ie du Q uebec ( r a m q ).
2.2 Case Identification and Data Collection Methods T h e case g ro u p co n sisted o f w om en d iag n o sed w ith p rim a ry h isto lo g ically co n firm ed cca at a M ontreal or L aval hospital b etw e en 1998 and 2004 (Table i). T h e w o m en h ad b een resident in th o se regions for a m in im u m o f 5 y ears before an d at diagnosis. U sing the In tern a tio n a l C lassification o f D iseases, 9 th revi sion, co d es 180.0—180.9, cases w ere identified by the p ro v in cial tu m o u r re g istry and by m ed ical records d ep a rtm en ts at 18 hospitals th at review P ap sm ears and th at o ffer d iag n o stic and trea tm e n t serv ices for c c a in g re a te r M o n trea l. R e c o m m e n d a tio n s state th at screen in g can stop at age 70 if a w om an has h ad at least 2 satisfactory, cy to lo g ically n o rm al Pap sm ears in the p re ced in g 9 y ea rs and has n ev er had a b io p sy -co n firm e d p re c u rso r lesion5,6. N e v erth eless, inclusion o f w o m en into the case g roup w as not re stricted b y age, b ecau se fu lfillm e n t o f those crite ria co uld not be d eterm in ed w ith c e rtain ty based on data co llected d u rin g th e study. D ata collected included d ates an d re su lts o f Pap tests, d iag n o stic p ro ced u res, an d tre a tm e n ts for p rein v asiv e cervical lesions (in cluding nam es o f physicians p erfo rm in g the services, and n am es o f h o sp ital laboratories w here specim ens w ere ex am in ed ) and d em ographic ch a rac te ristic s o f th e stu d y subjects. U sin g a sp ec ia lly d esig n ed , p ilo t-te ste d form , tra in e d a b s tra c to rs in itia lly c o lle c te d d a ta fro m m ed ical ch a rts at th e hospital th at d iag n o sed each case. T h e in fo rm atio n from the ch a rts th en guided th e ab stra cto rs to o th er hospitals at w hich to review ch arts. A b o u t 14% o f ch a rts w ere rev iew ed at least tw ice. T he q u ality o f d ata collection w as assessed by d eterm in a tio n o f inter- and in tra-a b stracto r relia b ili ties at several p o in ts d u rin g the data collection phase.
H o sp ital cy to lo g y an d p a th o lo g y la b o ra to rie s provided re p o rts o f P ap tests and cca-related p ro c e dures. T elephone in terv iew s o f p atien ts in the case group (or th e ir proxies) w ere co n ducted by tra in e d in terv iew ers u sin g a stru c tu re d q u estio n n aire th at w as p ilot-tested on w om en w ho w ere sim ilar to the w om en in the case g roup and w ho had b een d iag n osed w ith cca in 1997. To o b tain a d escrip tio n o f all cases o f cca o c c u rrin g w ith in the tim e an d region o f interest, an abb rev iated version o f the q u estio n n aire (dem ographic inform ation only) w as ad m in iste red to sh o rt-term resid en ts o f M ontreal an d Laval w ho m et all o th er elig ib ility criteria. F am ily physicians and gynecologists com pleted a self-adm inistered questionnaire and provided copies o f laboratory reports for Pap tests and other cervixrelated procedures. Physician m edical billing records obtained from the r a m q consisted o f all m edical ser vices reim bursed for each w om an in the case group w ith in the 5 years before diagnosis, including the date o f each service and the m edical specialty o f the physician w ho perform ed the service. N o r a m q code specific to perform ance o f a Pap test exists; hence, m edical billing records could not be used to determ ine screening histories.
2.3 Auditing of Pap Screening History for the Case Group E ac h c a se -sp e c ific o b s e rv a tio n w in d o w c o n sis te d o f tw o p e rio d s , as d e p ic te d in F ig u re 1. T h e d ia g n o stic p e rio d w a s b o u n d e d b y th e d a te o f d ia g n o sis (th at is, d a te o f th e first p ro c e d u re p ro v id in g h isto lo g ic p r o o f o f cca) a n d th e d a te o f th e first c y to lo g ic a lly a b n o rm a l o r e q u iv o c a l P ap sm e a r w ith in 5 y e a rs p re c e d in g d ia g n o sis. T h a t P ap te s t w a s te rm e d th e “ tr ig g e r P a p ” b e c a u s e it i n i t i ated th e e n su in g c a sc a d e o f fo llo w -u p p ro c e d u re s le a d in g to th e c c a d ia g n o sis. To be c a te g o riz e d as th e trig g e r P ap, th e te s t h ad to b e th e o n ly c e rv ix re la te d p ro c e d u re p e rfo rm e d th a t sam e day. T h e p re -d ia g n o s tic p e rio d c o n s is te d o f th e tim e fro m th e d a te o f th e trig g e r P ap to th e b e g in n in g o f th e o b se rv a tio n w in d o w — th a t is, th e s ta rtin g d ate o f th e 5 y e a rs p re c e d in g th e d ia g n o sis d ate. To av o id c o n sid e rin g th e P ap te s ts th a t fo rm e d p a rt o f th e final w o rk -u p to w a rd th e c c a d ia g n o sis, th e d e te r m in a tio n o f P ap s c re e n in g h is to rie s w a s lim ite d to s c re e n in g th a t o c c u rre d d u rin g a n d p re c e d in g th e p re -d ia g n o s tic p e rio d . W om en w ere ca teg o rized as “ever sc re e n e d ” if th ey h ad a Pap te st classified as cy to lo g ically norm al d u rin g the p re -d iag n o stic p erio d o r i f they h ad Pap tests o f any resu lt before the p re -d iag n o stic p erio d (or both). T hey w ere categorized as “nev er screen e d ” i f there w as no evidence o f P ap screen in g w ith in or before the p re -d iag n o stic p erio d a n d i f the w om an (or h er proxy) said d u rin g the in terv iew th at she h ad never been screened d u rin g h er lifetim e. W om en w ho
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DETERMINANTS OF CERVICAL CANCER RISK
w ere classified as “ever screened” w ere fu rth e r cat egorized based on the tim e in terv al b etw een date o f diagnosis and either the last Pap test considered norm al ( if it o ccu rred d u rin g the p re-d iag n o stic table
i
Description of the case and control groups of the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004 Descriptor
Cases
Controls
Subject identification
Quebec Tumour Registry and medical records departments at hospitals
Subject inclusion criteria
Diagnosed with a primary, histologically confirmed cervical cancer at a Montreal or Laval hospital during 1998-2004 Resident in the region for a minimum of 5 years before and at diagnosis
Data sources
Abstraction of data from hospital medical charts Reports obtained from hospital cytology and pathology laboratories Telephone-based interviews of cases or proxies Self-administered questionnaire completed by family physicians and gynecologists Physician medical billing records from the ra m q (dates and procedure codes for all medical visits by each patient in the 5 years preceding the index date, including the medical specialty of the physician handling the visit)
cchs
p eriod) or the last Pap test o f any resu lt (if it o c cu rred before the p re-d iag n o stic period). Classification o f each wom an’s Pap screening his tory was based on at least one o f the following sources
Group 1
Group 2
Statistics Canada, 2003 cchs (cycle 2.1)
Physician medical billing records from the ram q
Female residents in Montreal Using each date of a histologic or Laval who participated in cervical cancer diagnosis (case) the 2003 cchs as an index date, the ra m q provided a random sample of women without cervical cancer who were individually matched (1:1) to the women with cervical cancer by age (within 5-year age groups) and region of residence (Montreal or Laval) Responses to the 2003
cchs
Physician medical billing records from the ra m q (dates and procedure codes for all medical visits by each control subject in the 5 years preceding the index date, including the medical specialty of the physician handling the visit)
= Canadian Community Health Survey; ra m q = Regie de l’assurance maladie du Quebec.
Pap tests of any result
-5
One or more cytologically normal Pap tests
D e fin itio n o f Ever Screened
Time prior to diagnosis (years)
A First abnormal Pap test ('Trigger Pap’)
Date of diagnosis
Diagnostic Period
Pre-Diagnostic Period
D e fin itio n
No Pap tests founda
«■
*■
of N ever Screened
1 Periods o f observation and operational definitions o f “ever screened” and “never screened.” a In addition, the woman in the case group (or her proxy) must have completed the subject questionnaire and must have stated that she was never screened.
f ig u r e
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SPENCE et al.
(listed in d eclin in g order o f reliability): laboratory rep o rt (obtained d irectly from a hospital laboratory, found in the hospital chart, or sent to us by a physi cian) and a secondary source (physician questionnaire, an n o tatio n w ith in the m edical chart, or case or proxy interview ). B ased on the sources o f data available for a given w om an and the concordance o f results betw een them , the term s “definite,” “probable,” and “possible” w ere u sed to indicate the degree o f confidence attained in the classification o f each w om an’s screening history, w ith th e first and last term s indicating the m o st and least d eg rees o f con fidence respectively. H isto ries deem ed as “definite” w ere u sed in the analyses.
(cis) for asso ciatio n s b etw e en c h a rac te ristic s o f the stu d y subjects an d c c a (overall an d by c a n c e r stage). T he o rs w ere ad ju sted for age (±5 years) at d iagno sis for the case g roup and at tim e o f in terv iew for control group 1. D eg ree o f invasion w as classified as lo cal ized (In te rn a tio n a l F ed eratio n o f G y n e co lo g y and O b stetrics stages i a I , ia 2 , i b ) , reg io n al (stages i i a , i i b , i i i a , i i i b ) , o r d istan t (stage iv)8. F or m o d ellin g , the first tw o categories w ere g ro u p e d an d co m p ared w ith the th ird category. S creening h isto ry w as categ o rized in th ree ways: • •
2.4 Control Identification and Data Collection Methods • C o n tro l su b jects w ere d eriv e d fro m tw o so u rc es, as n o ted in Table i. W om en re sid in g in M ontreal or L aval w ho p a rtic ip a te d in the 2003 (cycle 2.1) C a n ad ian C o m m u n ity H ealth S urvey ( c ch s ) co m p rised one co n tro l g ro u p (control g roup 1). T he c ch s is a g o v e rn m e n t-in itia te d c ro ss-se c tio n a l su rv e y th a t o b tain s health in fo rm atio n ab o u t C an ad ia n s7. T hese control subjects w ere not interview ed by o ur research staff; in stead , th eir responses to c ch s questions about d em o g ra p h ics a n d P ap sc re e n in g u tiliz a tio n w ere co m p ared w ith the sam e d ata for the w om en in the case g roup w ho resp o nded to the ic c a s questionnaire. It should be n o ted th at the p e rtin e n t q uestions in the c ch s and the ic c a s h ad essen tially the sam e w ording; any d iffe ren c es w ere in consequential. A second co n tro l g roup (control g roup 2) w as d eriv ed fro m d ata held by the r a m q . U sing the date o f h istolo g ic d iag n o sis w ith cc a for each w o m an in th e case g ro u p as th e index date, the r a m q pro v id ed a ra n d o m sam ple o f w om en w ith o u t cc a w ho w ere in d iv id u ally m atch ed (1:1) to cc a cases b y age (w ithin 5-year age groups) an d region o f residence (M ontreal o r L aval). T h e r a m q pro v id ed the d ates an d p ro c e d u re co d es o f all m ed ica l serv ices th at the control subjects received in the 5 y ears before the index date, in clu d in g th e m ed ical sp ecialty o f th e p h y sician w ho p ro v id ed each serv ice. C o n tacts w ith fa m ily physi cians, gynecologists, and o ther m edical specialists for the control subjects w ere then counted and com pared w ith the m ed ical co n tac t profiles before diag n o sis o f the w om en in the cca case group. E thics approval w as o b tain ed fro m p e rtin e n t in stitu tio n s and hospitals, and signed inform ed consent w as o b tain ed from all subjects. W om en in the case g ro u p or th e ir p ro x ies w ere co n tacted only i f physi cian s p ro v id ed sig n ed perm ission. T he C om m ission d ’acces a l’info rm atio n approved receipt o f d ata from th e Q u eb ec tu m o u r re g istry and r a m q . 2.5 Statistical Analysis U n c o n d itio n al logistic reg ressio n w as u se d to esti m ate o d d s ra tio s ( o r s ) and 95% confidence in terv als
Lifetime screening history (never, ever, unclassified) T im e since last P ap te st (80 Years Age at diagnosis (years) Median Mean Range Presence of symptomsb [n (%)] Yes No Unknownc Symptom type, when present Vaginal discharge Bleeding Vaginal, intermenstrual Vaginal, postmenopausal Vaginal, postcoital Menstrual, heavy or prolonged Abnormal, type unspecified Loss of appetite Weight loss Fatigue Paine Other symptoms Disease stage [n (%)] ia I ia 2
IB II III IV
Unknown Tumour histology [n (%)] Squamous cell Adenocarcinoma Adenosquamous Other less common types Unknown
Valuea 23 (4.0) 91 (16.0) 137 (24.1) 103(18.1) 76 (13.4) 86 (15.1) 52 (9.2) 52 55 22-94 399 (70.2) 51 (9.0) 118(20.8) 69 (17.3) 101 (25.3) 200 (50.1) 68 (17.0) 12 (3.0) 5 (1.3) 15 (3.8) 64 (16.0) 18 (4.5) 95 (23.8) 45(11.3) 89 (15.7) 31 (5.5) 173 (30.5) 113 (19.9) 105 (18.5) 42 (7.4) 15 (2.6) 410 (72.2) 123 (21.7) 16 (2.8) 14 (2.5) 5 (0.9)
a Percentages may not add up to 100 because of rounding. b Including abnormal vaginal discharge, intermenstrual vaginal bleeding, postmenopausal vaginal bleeding, heavy or prolonged menses, postcoital vaginal bleeding, loss of appetite, weight loss, fatigue, pain (pelvic, abdominal, back, or leg), and other less common symptoms. The “other” category includes anemia, dyspareunia, dysuria, hematuria, rectal bleeding, urinary or renal tract problems, ascites, and vesicovaginal fistula. c Data indicating the presence or absence of a particular charac teristic were not found in the medical chart. d Subject could have experienced more than 1 symptom («=399). e Pelvic, abdominal, back, leg, or unspecified location.
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Associations between demographic characteristics of the study subjects and cervical cancer in the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004
table hi
Characteristic
Place of birth Canada Other If not Canadian-born, time in Canada 0-9 Years >10 Years Marital status Married Common-law Widowed, separated or divorced Single Language of conversation English and French'1 English, not French'* French, not English'1 Neither English nor French Employment status Employed Unemployed, homemaker Student Retired Highest level of education Less than secondary graduation Secondary graduation Some postsecondary education Postsecondary degree or diploma Smoking status Never-smoker Current smoker Former smoker Childbirth in preceding 5 years No Yes Had a regular doctor No Yes Chronic condition No Yes
Study group [ n
(% )]
95% c i c
or
Casesa
Controlsb
256 (71.1) 104 (28.9)
1442 (77.4) 421 (22.6)
Reference 1.4 1.1 to 1.8
22 (23.9) 70 (76.1)
109 (26.4) 304 (73.6)
1.5
126 (34.9) 61 (16.9) 107 (29.6) 67 (18.6)
662 (33.5) 215 (10.9) 587 (29.7) 513 (25.9)
Reference 1.6 1.1 to 2.3 1.1 0.8 to 1.4 0.9 0.6 to 1.2
136 (37.8) 37 (10.3) 173 (48.1) 14 (3.9)
1034 (55.4) 153 (8.2) 653 (35.0) 28 (1.5)
2.0 2.1 4.5
206 (57.5) 67 (18.7) 8 (2.2) 77 (21.5)
940 (58.1) 284(17.5) 41 (2.5) 354 (21.9)
Reference 1.0 0.7 to 1.4 1.7 0.8 to 4.0 0.4 0.3 to 0.7
107 (30.9) 72 (20.8) 68 (19.4) 99 (28.6)
498 (25.5) 251 (12.9) 105 (5.4) 1096 (56.2)
0.9 2.4 0.3
131(40.1) 123 (37.6) 73 (22.3)
676 (34.2) 537 (27.2) 763 (38.6)
1.1 0.4
Reference 0.8 to 1.5 0.3 to 0.6
294 (89.4) 35 (10.6)
887 (82.7) 186 (17.3)
1.3
Reference 0.9 to 2.1
95 (29.7) 225 (70.3)
408 (20.6) 1574 (79.4)
1.9 1.4 to 2.5 Reference
246 (75.5) 80 (24.5)
448 (22.6) 1534 (77.4)
13.4 10.0 to 18.0 Reference
0.8 to 2.9 Reference
Reference 1.4 to 3.1 1.6 to 2.7 2.3 to 9.1
Reference 0.6 to 1.3 1.6 to 3.6 0.2 to 0.4
a Women with invasive cervical cancer for whom data from the subject interview were available. These women might or might not have lived in Montreal or Laval for at least 5 years («=362). For some questions, numbers might not total to 362 because of nonresponses. The smoking status, childbirth, regular doctor, and chronic condition analyses include only women who resided in Montreal or Laval for a minimum of 5 years before diagnosis because only those women completed the long version of the questionnaire («=330). b Women living in Montreal or Laval who responded to Statistics Canada’s 2003 Canadian Community Health Survey. c Models were adjusted for age (20-24, 25-29, 30-34, ..., >80 years) at diagnosis (cervical cancer patients) or at time of Canadian Community Health Survey completion (controls). d Might also speak another language. or = odds ratio; ci = confidence interval.
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had a statistically significantly greater risk o f cca. This increased cca risk w as present up to 9 years a fte r im m ig ra tio n to C anada. S p eak in g neith er E nglish nor French, having som e p o stseco n d ary education, not having a regular doctor, and not hav ing a chronic condition were all associated w ith a statistically significant greater risk o f cca. There was also a statistically nonsignificant indication that the risk o f advanced cca was greater in m ore recent im m igrants and in those w ithout a regular doctor (data not shown). For the study group, Table iv shows Pap screen ing histories and their associations w ith cca risk. M ost w om en in the case group had been screened at least once in their lifetim e, w ith the frequency v ary in g from 84.8% to 90.4% depending on the
analysis. A n e stim a te d 30.9% —56.8% had b een screened w ith in 3 years o f diagnosis. W hen all sources o f data w ere used to determ ine screening histories o f the w om en in the case group, a statisti cally significant increased cca risk w as associated w ith b e in g ev er-screen ed co m p ared w ith b ein g never-screened. W hen the case group was restricted to w om en whose screening categorization w as clas sified as “definite,” the point estim ate w as lower and no longer statistically significant, but it rem ained above 1. W hen screening histories in the case group w ere lim ited to data obtained solely from the iccas questionnaire, being ever-screened appeared to be associated w ith a low er cca risk, although the result ju st bordered on significance. M oreover, the longer the tim e interval since the last Pap test, the greater
iv Associations between screening history (Pap tests) and cervical cancer in the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004
table
Pap screening history
Screening variable Based on all sources o f data Casesa /n (%>)]
Controls'0 [n (%>)]
Adjusted0 or
Based on all sources o f data and screening history reliability deemed “definite ”
95% c i
Adjusted0
Casesa [n (%)] OR
Screening classification Never Ever Not classified11 Time since last screen for the ever-screened6 80 years). d Based on available data, the screening histories of 161 women could not be classified as “ever” or “never” screened. However, it was determined that they had not been screened within the 5 years preceding their diagnosis with cervical cancer. e Refers to women who were “ever” screened in the past. f “Inadequate” includes women in the case group who were never screened, who were screened within 5 years of diagnosis (but not within 3 years), who were screened more than 5 years before diagnosis, and for whom ever or never screening could not be determined, but for whom no screening in the 5 years preceding diagnosis could be determined. Subjects categorized as “ever screened,” but whose time since the last normal screen could not be defined were omitted («=6). For Canadian Community Health Survey respondents (control group 1), “inadequate” refers to women never screened and to those whose last screen occurred between 3 and 5 years or 5 or more years in the past. “Adequate” refers to patients screened within 3 years of their diagnosis. Adequacy was defined based on prevailing clinical practice guidelines. or = odds ratio; ci = confidence interval; na = not applicable. I C urrent O ncology — V olume 21, N umber 6, December 2014 I Copyright © 2014 Multimed Inc. Following publication in Current Oncology, the full text of each article is available immediately and archived in PubMed Central (PMC).
SPENCE et al.
th e risk o f c c a, a fin d in g th a t w as e sp e cially ev id en t w h en th e ca se g ro u p w as lim ite d to w om en w hose screen in g cate g o riza tio n w as deem ed “definite.” A ll th re e an a ly se s fo u n d th a t an in a d e q u a te sc re e n in g h is to ry w as asso c ia te d w ith a sta tistic a lly sig n ifi ca n tly g re a te r ris k o f cca. S im ilarly, n ev e r b ein g screen e d o r th e p assa g e o f 5 or m ore y ea rs since last sc re e n in g w ere a sso c ia te d w ith an in c re a se d risk o f b ein g d ia g n o se d w ith re g io n a l o r d ista n t c c a ra th e r th a n lo c a liz e d c a n c e r (data n o t show n). A s T able v show s, h a v in g receiv ed care from a g y n ec o lo g ist w as asso ciated w ith a low er risk o f d ev eloping cca, even a fte r co n tro llin g for visits to o th er p hysicians. In co n trast, a g re a te r risk o f cca w as observed i f care w as received from other m edical sp ecialists o r fro m fam ily physicians.
4.
DISCUSSION
O u r stu d y u n d e rsc o re s the im p o rta n c e o f re g u la r screening for the prevention and early diagnosis o f cca. M ost w om en in the case group had undergone a Pap test at least once in th eir lifetim e (85% -90% ). However, depending on the sources o f data used for de term in in g screening, 4 3 % -6 9 % o f those w om en w ere not screened w ith in 3 years o f diagnosis, and overall, an estim ated 53% —'74% had an inadequate screening history. T hose findings em phasize the failings o f o p p o rtu n istic Pap screening and h ighlight the need for screening w ith in the context o f an organized program
table
v
that has the m eans to invite w om en population-w ide to screening and to recall w om en for screening at ap propriate intervals. C o m p a re d w ith C a n a d ia n -b o rn w o m e n , im m ig ra n ts have a h ig h e r c c a risk , w h ich m ig h t be attrib u te d to p o o re r use o f sc re e n in g 9-14. C u ltu ral v a lu e s, b eliefs ab o u t se x u a l b eh a v io u r, la n g u a g e b arriers, fatalism , ac cu ltu ratio n , and lack o f k n o w l edge about cc a influence the u se o f Pap screen in g by im m ig ra n ts15-18. T he cca risk am ong im m ig ra n ts a p p e a rs to b e lo w er w ith len g th o f tim e liv ed in C an ad a , w hich m ig h t be a ttrib u ta b le to a g re a te r likelihood o f screen in g use in long-term im m ig ra n ts th an in re cen t im m ig ra n ts9’19,20. L an g u ag e b a rrie rs 10 and low er edu catio n level10,12,21 are asso ciated w ith g re a te r risk o f cca, likely b ec au se o f p o o r u se o f Pap sc re e n in g 9,10,20,22,23. T he stu d y re su lts also echo e a rlier fin d in g s9,10,20 in h ig h lig h tin g the im p o rtan ce to ap p ro p riate screen in g o f h av in g a re g u la r doctor. R eceipt o f care from a gynecologist, independ en t o f o th er physicians, w as asso ciated w ith a low er risk o f cca. C o m p ared w ith fam ily physicians, g y n e c o lo g ists are m ore likely to p erfo rm Pap te sts24,25, and w om en w ho w ish to have Pap tests p re fere n tia lly go to g y n eco lo g ists in stead o f fam ily phy sician s to be screened24,26. W e speculate that, because slightly less co n tact w ith gynecologists w as seen in w om en in the case group th a n in the control group, th e w om en in the case g roup w ere less likely to be screen ed and w ere, as a result, at g re a te r risk o f cca.
Associations between physician visits and cervical cancer in the Invasive Cervical Cancer Study, Montreal, Quebec, 1998-2004 Practitioner type
Family physician 0 Visits 1 to 2 Visits 3 to 4 Visits >4 Visits Gynecologist 0 Visits 1 to 2 Visits 3 to 4 Visits >4 Visits Medical specialist other than gynecologist 0 Visits 1 to 2 Visits 3 to 4 Visits >4 Visits
Study group
or
95% ci
Adjustedb
Cases a [n (%)]
Controls [n (%)]
54 (9.6) 65(11.6) 55 (9.8) 388 (69.0)
146 (26.0) 53 (9.4) 49 (8.7) 314 (55.9)
Reference 4.8 2.7 to 8.4 4.4 2.4 to 7.9 5.2 3.3 to 8.2
Reference 3.6 2.0 to 6.6 3.4 1.8 to 6.6 4.3 2.4 to 7.6
355 (63.2) 110(19.6) 38 (6.8) 59 (10.5)
345 (61.4) 75 (13.4) 58 (10.3) 84 (15.0)
Reference 1.4 1.0 to 1.9 0.6 0.4 to 0.9 0.7 0.5 to 1.0
Reference 0.9 0.6 to 1.3 0.4 0.2 to 0.7 0.5 0.3 to 0.7
86 (15.3) 110(19.6) 65 (11.6) 301 (53.6)
172 (30.6) 67(11.9) 47 (8.4) 276 (49.1)
Reference 4.1 2.6 to 6.4 3.6 2.2 to 5.9 2.8 1.9 to 4.0
Reference 2.4 1.4 to 4.0 2.0 1.1 to 3.5 1.7 1.0 to 2.8
or
95% c i
a Of 568 patients who met the study inclusion criteria, 6 did not have a ra m q number. Matched controls were not obtained for the latter 6 patients, thus leaving 562 cases and 562 controls for analysis. b Each model was adjusted for the number of visits to other physician types, using the 0, 1-2, 3-4, >4 categories. or = odds ratio; ci = confidence interval. ______________________________________________________C urrent O ncology — V olume 21, N umber 6, D ecember 2014 Copyright © 2014 Multimed Inc. Following publication in Current Oncology, the full text of each article is available immediately and archived in PubMed Central (PMC).
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H av in g h ad sp ec ia list v isits w as asso ciated w ith a n in c re a s e d risk o f cca. C o m p ared w ith w om en n o t h a v in g c h ro n ic c o n d itio n s, w o m en w ith such co n d itio n s u n d erg o an y ty p e o f screen in g less often, esp e cially i f p hy sician s believe th at th o se w om en h av e a sh o rten ed lifesp an 27’28. T herefore, if, before d iag n o sis, ch ro n ic m orbidities th at re q u ire d care by sp ecialists w ere m o re p re v alen t in the case group th a n in th e co n trol group, it is plausible to assum e th at w o m en in th e case g roup w ould be less likely to receiv e P ap screen in g b ecau se o f the em phasis the specialist m ight have placed on properly investigating an d tre a tin g th e ch ro n ic condition. A low er o p p o rtu n ity to screen could co n seq u en tly have co n trib u ted to an in cre ased risk o f b ein g d iag n o sed w ith cca. A lth o u g h th is exp lan atio n is plausible, it m ig h t not a c tu a lly b e ap p licab le to o u r c o h o rt, b ec au se o u r stu d y fo u n d th at w om en in the case g roup re p o rted ch ro n ic d isease s less freq u en tly th a n did w om en in th e co n tro l group. H ow ever, th at fin d in g w as based on a su b g ro u p o f the case g roup w ho resp o n d ed to th e icca s q u e s tio n n a ire . T h o se w o m e n te n d e d to b e y o u n g er an d w ere p erh ap s less lik ely th a n the w o m en w ho did no t p artic ip a te in the su rv ey to have a ch ro n ic disease.
5.
STUDY LIMITATIONS AND STRENGTHS
L ack o f d ata p rev en ted a d e te rm in a tio n o f the life tim e screen in g h isto ries o f 161 w om en in the case g ro u p , w h ic h c o u ld u ltim a te ly h av e re s u lte d in o v erestim a tio n o f the p ro p o rtio n o f cases considered “ev er screen ed .” W om en in the case g roup w ith an u n classified h isto ry w ere d em o g ra p h ically sim ilar to w om en w ho ten d ed to have a p o o r Pap screen in g h isto ry (d ata n o t show n); hence, w e believe th at the w o m en w ith an u nclassified h isto ry w ere m o st likely to have b een n ever-screened. F urther, to be classified as n ev er-screen ed , w om en in the case group or th e ir p ro x ies m u st have re sp o n d ed to the iccas q u estio n n aire b y say in g th at th ey h a d n ever b een screened. W om en in the case g roup w ith unclassified screening h isto ries w ere less likely th an those w hose screen in g h isto ries w ere classified to have p artic ip a te d in the in terv iew (21.7% an d 72.5% respectively). H ence, al th o u g h w e did not find any evidence o f P ap screening befo re d iag n o sis, the 161 w om en in the case group co u ld n o t have b ee n classified as nev er-screen ed i f no in terv iew to o k place. B e c a u se m u ltip le d a ta so u rc e s w ere u se d for th e case h isto rie s, d iffe ren tial m isclassificatio n o f s c re e n in g h is to rie s m ig h t h av e a ffe c te d th e P ap s c re e n in g —c c a a sso c ia tio n s. W h e n d a ta fro m all so u rces w ere u sed to classify u se o f screen in g by w o m en in th e case group, the ten d en c y to ca te g o riz e th o se w o m en as ever-screened a p p e are d to be a g re a te r th a n it w as for w om en in the control group, w h ich re su lted in the o dds ratio b ein g g re a te r th an 1. T h at o b serv atio n m ig h t be attrib u tab le to the m ore
ex h au stiv e search for d ata and the v ario u s co n tex ts in w h ich d ata collection o c c u rre d for the case group. In co n trast, screen in g h isto ries in the contro l g roup w ere b ase d solely on re sp o n se s to the c c h s q u es tio n “H ave you ever h ad a P ap te st? ” T he o d d s ratio d eclin ed slightly in the an aly ses w h en the screen in g h isto ries u sed for the case g roup w ere th o se d eem ed to be “definite,” w hich is pro b ab ly reflective o f the g re a te r o b jectiv ity o f lab o ra to ry re p o rts co m p ared w ith o th er d ata sources. L ikew ise, the asso ciatio n b etw e en tim e since the last P ap test an d cca, w h en b ase d on all sources o f d ata, m ig h t also h av e b een affected by d ifferen tial m isclassificatio n b ec au se o f the m ultiple sources o f d ata for the case group. S ocial d e sira b ility bias a n d te le sc o p in g co uld have led subjects to re p o rt th eir last Pap test as o ccur rin g m ore recen tly th a n it a c tu a lly h ad , re su ltin g in an underestim ation o f tim e since the last Pap test29-31. Such b iases w ould have m o st affected the an aly ses b ase d on the iccas q u estio n n aire and the c c h s . T h e iccas q u estio n n aire re sp o n se ra te (64.8% ) m ig h t be a lim itatio n . H ow ever, th at ra te is h ig h er th an the rates in m an y sim ilar stu d ies th at in clu d ed cca c a ses32-35, an d although som e w om en in th e case g ro u p did no t re sp o n d to th e iccas q u estio n n aire , screen in g h isto ries could still be o btained fro m o th er d ata sources. O th er lim itatio n s in clu d ed th e ro u tin e d iscard in g b y physicians o f m edical files a fte r 5 years o f dorm ancy and the p o o r organization, m issing lab o ra to ry re p o rts, an d illegible h a n d w ritin g th at o ften c h a ra c te riz e d h ospital m edical charts. A lso , som e lab o rato ries re fu se d to provide re p o rts to o u r study, and o f th o se th at did, m an y did no t have co m p u ter ized system s and h ad m issin g records. S tudy stren g th s include a large stu d y p o p u latio n w ith com plete case asc ertain m en t, an extensive audit p ro cess for d ata retriev al (m ultiple sources o f d ata accessed), an d atten tio n to d ata q u ality th ro u g h s ta ff tra in in g an d co n tin u o u s m o n ito rin g o f d ata co llec tion. A lth o u g h technologies for cc a prevention m ig h t change in fu tu re, the im plications o f o u r stu d y w ould still be applicable.
6. CONCLUSIONS A g re ater cc a risk w as asso ciated w ith a p erio d o f 3 or m ore years since the last P ap test (com pared w ith screen in g in the p re ced in g 3 years). Im m ig ran t w om en, less ed u cated w om en, an d w o m en w ith la n g u ag e b a rrie rs w ere at g re a te st risk o f cca, as w ere w om en w ho receiv ed care fro m m edical sp ecialists o th er th a n g y n eco lo g ists an d fro m fam ily p hysicians in the 5 years p re ced in g diag n o sis (case group) or c c h s in terv iew (control group 1). O u r findings un d er score the im p o rtan ce o f provider education to prevent m isse d o p p o rtu n itie s for c c a screen in g w h en at-risk w o m en seek m edical atten tio n an d pro v id e fu rth e r evidence o f the n eed for an o rg a n iz ed p o p u latio n b ased screen in g program .
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SPENCE etal.
T he p rev en tio n o f invasive cc a re q u ires not only ad o p tio n o f th e P ap test, but also ap p ro p riate refer ral and trea tm e n t o f cerv ical in traep ith elial lesions b efo re th ey p ro g re ss to invasion. A n au d it o f the a p p ro p riaten ess o f such d o w n stre am p ro c esses o f care is w a rra n te d in the fu tu re, p a rtic u la rly as new screen in g tech n o lo g ies— for exam ple, testin g for h u m an p ap illo m a v iru s— b eco m e p a rt o f the stan d ard o f care.
7. ACKNOWLEDGMENTS T h e au th o rs ack n o w ledge and th a n k the follow ing p eo p le for th e ir in v aluable co n trib u tio n s to the su c cessfu l ex ecu tio n an d com pletion o f the iccas study: Dr. A lex F erenczy, Dr. M a rtin D aw es, Dr. G erald S tan im ir, Dr. P a rv iz G h a d iria n , Dr. F rancois L eh m an n , Dr. F lav ia D a Silva, M s. C laude R ich ard , and th e m an y p ath o lo g ists an d m edical reco rd s te c h n i cians at th e G re ater M o n treal an d L aval hospitals. A m o st h e a rtfelt th ank-you is also ex tended to the stu d y subjects an d th eir n ex t o f k in w ho p artic ip a te d in o u r study. T h is stu d y w as su p p o rte d fin an c ially th ro u g h g ra n ts from th e C an ad ian In stitu te s o f H ealth R e search (IH S-61108, M O P -64454, an d C RN 83320).
8. CONFLICT OF INTEREST DISCLOSURES E L F has no co n flicts o f in tere st w ith re sp e c t to the c o n te n t an d m essag e o f th e p re se n t w o rk , b u t he re p o rts h av in g serv ed as o ccasional p aid co n su ltan t to co m p an ies involved w ith h p v v ac cin atio n (M erck, G la x o S m ith K lin e ) a n d c e rv ic a l c a n c e r sc re e n in g (R oche, BD, Q iagen, G en-Probe). H is in stitu tio n has receiv ed th re e g ra n ts from M erck in p artia l su p p o rt o f research th at he initiated. A A declares no conflicts o f in tere st w ith re sp ect to the co n ten t an d m essage o f th e p re sen t w ork, but his in stitu tio n has received a g ra n t from G lax o S m ith K lin e in su p p o rt o f o th er u n re la ted research . N o o th er authors h ad financial co n flicts o f in tere st to declare.
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C orrespondence to: A ndrea Spence, D ivision o f C ancer Epidemiology, 546 Pine Avenue W est, M on treal, Quebec H2W 1S6. E -m ail: andrea.spence@ m ail.m cgill.ca *
Division o f C ancer Epidemiology, M cG ill U ni versity, M ontreal, QC. t D epartm ent o f O bstetrics and Gynecology, King K h a le d U n iv e rsity H o sp ita l, R iy a d h , Saudi A rabia. J Division o f Gynecologic Oncology, Centre hospitalier de FU niversite de M ontreal, M ontreal, QC. § Institut national de sante publique du Quebec, M ontreal, QC. II D epartm ent o f O bstetrics and Gynecology, M c G ill U niversity Health Centre, M ontreal, QC. # D epartm ent o f Epidemiology, Biostatistics, and O ccupational Health, M cG ill University, M on treal, QC. ** D irection de sante publique de l’A gence de la sante et des services sociaux de M ontreal, M on treal, QC.
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