Dent. Oral Epidemiol.

{Key words: carcinoma; moulh,

1977: 5: 301-30(5


Etiological factors in oral squamous cell carcinoma R. M. BROWNE, M . C . CAMSEY, J, A. H . WATERHOUSE AND C . L, MANNING Department of Orat Patttotogy, University of Birmingham, Birmingttam and West Midtands Regiottat Cancer Registry, Birmingham, and North Staffordsttire Royat Infirmary, Stoke-onTrent, Engtand AI!STR/\(;T - A retrospective sun'ey of 75 patients with oral squamous cell carcinoma (ICD Nos. 143, 144, 145) resident in the County Borough of Stoke-on-Trent, England, and 150 controls has been earried otit by interview. The controls were matched for age, sex, occupation and place of residence. There was no difference in the prevalence or duration of denture wearing, although male controls had their dentures remade more frequently, Male patients practised oral hygiene procedures less frequently when they had their own teeth than controls. Habitual beer-drinking was more common and greater quantities were drunk by male patients than controls. Habitual cigarette smoking vvas less and pipe smoking greater among male patients than controls. Tobacco chewing, which was restricted to miners, was equally common (45 %) in the two groups. Among miners, the combined habit of tobacco chewing and pipe smoking was more common among patients (100%) than among controls (25 % ) , (Accepted for pubtication 13 August 1977)

In the period 1961-70, the incidence of squamous cell carcinoma (SCC) of the mouth (ICD, 8th ed,, 143-5) showed wide local variation from ageadjusted expcctatiotis in the West Midlands region of the UK, The greatest difference ( P < 0.001) was for Stoke-on-Trent (observed/expected = 45/ 22.77 - males; 17/11.30 - females), but there was no excess of SCC of tongue (ICD 141). Clinical observations suggested that the high incidence might be associated with the habit of tobacco chewing, commoti among miners in the area. Previous studies'*'"•"' have shown such an association, which is noted in particular for the verrucous form of SCC' . It was therefore decided to undertake a retrospective survey to investigate this and other possible etiological factors, by using cases notified to the Cancer Registry in the period 1957-71.

MATERIAL AND METHODS CANCER GROUP There was a total of 77 cases among residents of Stoke-onTrent in 1957-71, though one eould not be traced, and for

another the relative declined to cooperate in the survey. Consequently 75 subjects (46 male, 29 female) constituted the cancer group. CONTROL GROUP For each cancer patient, two controls, matched for age, se,\, occupation and residential area were selected. As the survey was retrospective, it proved impracticable to select as eontrols, subjects who had died in the same year as the cancer patients, but not as a consequence of oral squamous cell carcinoma. Instead, subjects living at the time of the sur\'ey (Oetober 1974-March 1976) were used as controls. The control subjects were seleeted by marking the location of the residence of each cancer patient on a street map of Stoke-on-Trent. These were grouped into eight approximately circular areas. From the records of a general medieal practice serving eaeh of the areas, two subjects were chosen at random to match each of the cancer patients, employing the following criteria. The age of the control was within 5 years of that of the eancer patient at the time of diagnosis. The controls were of the same sex and lived within a half-mile radius of the cancer patients, and had primary occupations similar to those of the cancer patients (see Table 1). Occupations vvere grouped into nine categories, as follows: mine workers, pottery vvorkei-s, munitions workers, armed forces, doiiiestic/shop/office workers, steel workers, farm workers, other faetory workers and others. The primary occupation vvas that in which each subject



Table 1, Di,stribution of primary, secondary and tertiary occupations among cancer patients (P) and controls (C) Females


Domestic/shop/of lice Mine workers Pottery workers Others None

Prii nary P C

Secondary C P

7 10

12 23

14 \5 0


2 4 2 27 11

42 0

7 14 7 45 19

Tertiary P C

Primary P C

Secondary P C 5 0 4 4 16



2 2 10 31


17 0



25 49

2 0

had spent most time. In addition details of secondary and tertiary occupations were recorded. There were 150 control patients, THE INTERVIEW The interviews were conducted by a specially trained interviewer aud were based ou a questionnaire. All the data collected were derived from verbal answers. The length of the interviews varied horn 1 to 3 hours. Of the cancer subjects, six males and seven females were still alive. In the case of the remaining 40 males and 22 females, the interview was with surviving relatives and/or friends. In several instances where one relative/friend was unable to provide full information, a second subject was interviewed to obtain specific details. For only two subjects was it necessary to travel outside Stoke-on-Trcnt, Of the control subjects, 90 males and 54 females were interviewed. For two males and four females, it was necessary to interview the relatives/friends of the subjects rather than the subjects themselves because of senility, HISTOLOGY No histological material was available in 19 cancer patients, the diagnosis being made on clinical grounds. Of the remaining 56 cases, the histological sections were reviewed and graded according to the criteria outlined by the WHO26. STATISTICAL ANALYSIS The data from the two groups were compared statistically by paired t-tests and y" analysis. In considering the results, it should be recalled that the eontrol group is twice as large as the cancer group.


0 0 0 3 26

11 0 7 9 31

1 0 1

1 55

EMPLOYMENT The maiti occupations among male patients were the pottery industry, mining industry atid domestic/ shop/office 'work and among female patients domestic/shop/office 'work and the pottery industry (Table 1). In total, 18 ( 3 9 . 1 % ) male patients had spent at least part of their life in the pottery industry and 16 (34.8 % ) in the mining industry, and 14 (48.3 % ) female patients in the pottery industry. DENTAL CONDITION There was no difference between the numbers of patients and cotitrols having their own teeth atid wearing dentures (Table 2 ) . In both groups full dentures were predomitiant, only three and six partial dentures being worn by male and female patients, and five and six by male and female controls, respectively. There was tio difference between the two groups in the type of material from which the denture was made, tior in the prevalence of clasps in partial dentures. Male cancer patients had worn dentures for 2 72 years, mean 26.1 years, and the controls for 2 -

Table 2. Number of individuals with teeth and wearing dentures among cancer patients and controls Own teeth

RESULTS AGE The age of the cancer patients ranged from 41 to 90 years (mean 70.0) for males and from 28 to 81 years (mean 64.0) for females. The age of the control subjects ranged from 41 to 91 years (mean 68.4) for males and from 37 to 83 years (mean 64.0) for females. Statistical analysis confirmed the similarit'y bet'ween the t'wo groups.

30 0 26 2

Tertiary P C

Males Patients'* Controls Females Patients Controls






14 22

30 70

30 74

14 18

6 12

23 46

27 52

2 6

* No data available for two male patients.

Etiology of oral carcinoma 303 Table 3, Frequency of toothbrushing aniong cancer patients and controls when they had their own teeth Occasionally Males Patients* Controls Females Patients* Controls

11 10

12 2

I/day 2/day 3/day

Table 4, Distribution of beer-drinking habits among cancer patients and controls


6 44







5 17

6 32





No data available for 11 male and four female cancer patients.

57 years, mean 30,0 years. Female cancer patients had worn dentures for 7-52 years, mean 34.0 years, and the controls for 2-52 years, mean 25.0 years. No differences were significant. Thirteen (28.3%) male cancer patients had 'worn more than one set of dentures compared with 49 (53.3 %) male controls. Similarly, 18 (62.1 %) female cancer patients had worn more than one set of dentures compared with 34 (58.6%) controls. This difference was statistically significant in male subjects {P < 0.05) but not in females. There was no difference between the two groups in their habits of cleanitig the dentures nor in whether they 'were worn at night or tiot. There were statistically significant differences in the frequency of toothbrushing (Table 3), taking those that brushed their teeth occasionally or not at all, -which were at the levels oi P < 0.01 for males, and P < 0.001 for females. Fewer male (20, 58.8 %) and female (19, 82.6 %) caticer patients used tooth-paste compared with male (70, 78.7 %) and female (51, 87.9%) controls, although this difference was not significant. Most subjects in both groups used no other oral hygiene procedure. Similar proportiotis of male (35, 97.2 %) and female (24, 96.0 %) patients and male (86, 93.5 %) and female (46, 83.6 %) controls did not visit the dentist regularly. ALCOHOL CONSUMPTION Although females compared well, the proportion of regular beer drinkers atnong male patients was significantly higher than in the controls (P < 0.001). Among regular drinkers beer consumption varied from 1.59 to 39 I/week, mean 8.2 I/week, and from 0 to 13 I/week, mean 4.0 I/week, for male and fe-




7 22


17 37




Males Patients* Controls Females Patients Controls




5 7

* No data available for one male patients.

male patients respectively and from 0 to 16 I/week, meati 4.7 I/week, atid from 0 to 6.5 I/week, mean 1.3 I/week, for male and female controls respectively (Table 4). The differetice between the two groups was statistically significant for males (P < 0.001) but not for fetiiales. There were only six (13.0 %) male and four (13.8 %) female regular spirits drinkers aniong the patients and 17 (18.5 %) male atid five (8.6 %) female among the controls. Regular spirit drinkers among male patients consumed oti average 0.60 bottles/week compared with cotitrols, mean 0.48 bottles/week. Regular dritikers among both female patients and controls consumed oti average 0.25 bottles/week. Further, there were otily one male and two female regular wine dritikers amotig the patients atid two male and one female among the controls. None of the male cancer patients had changed their drinking habits over their adult lifetime, compared with 21 (22.8%) controls ( P < 0.001). There was, however, no difference between female patients (1) and controls (2). TOBACCO CONSUMPTION There were significantly ( P < 0 . 0 5 ) fewer regular cigarette smokers among male patietits thati controls but not between females (Table 5). The mean cigarette consumption was 20.1 and 21. I/day for male and female patietits who smoked and 17.0 and 17.0/day for male and female controls respectively {P

Etiological factors in oral squamous cell carcinoma.

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