The changing pattern of neoplastic disease in Canadian Eskimos O. Schaefer,* md, frcp[c]; J.A. Hildes,! md, frcp[c]; L.M. MEDD,f md; D.G. Cameron,^ md, frcp[c]
Summary: The records of the two main referral centres for the western and central Arctic were reviewed for Eskimo patients with cancer diagnosed between 1949 and 1974 inclusive. To these were added the records for the past 6 years of patients from the eastern Arctic, giving a total of 180 histologically proved cases of malignant disease. The data were analysed for prevalence, relative frequency, geographic distribution and changes with time of the various neoplasms. Salivary gland and renal neoplasms have in recent years been displaced by cancer of the lung and uterine cervix as the most common malignant tumours in Canadian Eskimos. The prevalence of lung cancer in Eskimo women, particularly of the central Arctic, is striking. Cancer of the nasopharynx kept the same relative position during early and late years of the survey period. Breast cancer is still uncommon in Eskimos. Lactation rather than gestation history appeared to be an important protective factor. Cases of cervical cancer outnumbered those of breast cancer by 18 to 4, in sharp contrast to the relative proportions of these tumours in all Canadian women. Resume: Les changements dans les types de neoplasmes chez des Esquimaux canadiens Nous
avons
passe
en revue
les dossiers des malades
Esquimaux qui avaient ete envoyes aux deux centres specialises de I'Arctique occidental et central pour des cas de cancer, diagnostiques de 1949 a 1974 inclusivement. A ces cas sont venus s'ajouter les dossiers des malades referes pendant les 6 dernieres annees de I'Arctique oriental. Nous avions ainsi un total de 180 cas de tumeurs malignes, dont la nature etait demontree par histologie. Ces donnees ont ete analyses, du point de vue de la predominance, de la frequence relative, de la distribution geographique et des changements avec le temps des divers neoplasmes. Au cours des dernieres annees les neoplasmes des glandes salivaires et des reins ont ete remplaces par unit, northern region medical Canada, Charles Camsell Hospital, Edmonton; tnorthern medical unit, University of Manitoba, Winnipeg; and JThe Montreal General Hospital Reprint requests to: Dr. O. Schaefer, Northern medical research unit, Charles Camsell Hospital, 12815-115 Ave., Edmonton, Alta. T5M 3A4 From *the northern medical research services branch, Health and Welfare
un cancer des poumons et du col uterin qui sont devenus les tumeurs malignes les plus courantes chez les Esquimaux du Canada. La predominance du cancer pulmonaire chez les femmes Esquimaudes, surtout celles de I'Arctique central, est un fait particulierement frappant. Le cancer du nasopharynx a conserve la meme frequence relative pendant les deux periodes couvrant I'enquete. Chez les Esquimaux le cancer mammaire est encore tres rare. C'est I'allaitement maternal plus que le developpement de la grossesse qui nous parait etre le facteur protecteur essentiel. Le cas du cancer cervical depassent en nombre ceux du cancer mammaire dans la proportion de 18 a 4, ce qui contraste considerablement avec les proportions relatives de ces tumeurs pour I'ensemble de toutes les femmes Canadiennes.
Eskimos
were
probably
at no time free from
neoplastic
earlier Canadian medical1'2 and nonmedical3 observers. Fibiger4 in 1923 reported 14 cases of malignant disease diagnosed over a 10-year period in native Greenlanders, but the an¬ cestry of this group is partially European. For the next few decades the occurrence of tumours in apparently pureblooded Eskimos was considered rare enough to warrant publication of single case reports one of a "pure" Greenlandic Eskimo5 and one of a Canadian Eskimo.6 However, malignant disease was found at autopsy in 15 of 57 Alaskan Eskimos in 1956-58,7 in 11 of 90 Canadian Eskimos in 1951-608 and in 47 of 250 Eskimos and Aleuts in 1959-68.* Fortuine10 reviewed the data on 85 tumours diagnosed in southwest Alaskan Eskimos during 1957-67 in their main hospital and referral centre at Bethel and found, as did Hurst11 in an earlier report of 76 cases of malignant disease diagnosed over a 6-year period among all Alaskan Eskimos, a high prevalence of esophageal cancer. In Canada Schaefer1213 and Wallace and colleagues14 stressed the pre¬ valence of salivary gland tumours and the rarity of breast cancer15 in Eskimos. The present review draws attention to a remarkable change in the prevalence pattern of neoplastic disease ob¬ served over a 25-year period in Canadian Eskimos from different geographic areas with varying duration and in¬ tensity of acculturation.
disease, although this has been suggested by
some
CMA JOURNAL/JUNE 21, 1975/VOL. 112 1399
Material and methods
Patient records
were
reviewed in Charles Camsell Hos¬
pital and Dr. W.W. Cross Cancer Institute in Edmonton, and in the Health Sciences Centre, St. Boniface General Hospital and the Provincial Cancer Registry in Winnipeg. For these two centres we had confidence in the completeness of the review back to 1949, by which time a regular and persisting pattern of referral from the western and
central Arctic had been established. In a survey of the eastern Arctic the records of The Montreal General Hos¬ pital and sanatoria in Hamilton and Toronto were searched for histologically verified cases of neoplastic disease in Eskimos. For these referral centres it was not possible to be confident of the completeness of the survey for the years before 1967. Also, up to 1960 the eastern Arctic was less accessible to medical screening and evacuation of pa¬ tients; since then, regular services have operated. If our numbers are in error they are too low: at least a few patients probably died in the Arctic before their condition
the 7-year period 1967-73 are compared in Table II with those for all Canadians in the 5-year period 1968-72. The observed mortality exceeded significantly the expected rate for lung cancer in males and in females, for nasopharyngeal cancer in males and for salivary gland cancer in the two sexes considered together. For cancer of the ampulla of Vater, esophageal cancer and hepatoma the observed morTable I.Anatomic sites of 180 neoplasms in Eskimos of the Northwest Territories, proved histologically in Edmonton, Winnipeg, Montreal and Toronto in 1950-74*
diagnosed. Although we have included in the overall figures the 34 cases in eastern Arctic Eskimos the discussion of the chang¬ ing pattern of neoplastic disease in Eskimos is limited to was
the 146 cases in western and central Arctic Eskimos. We reviewed also the death certificates for the Northwest Territories from 1960, but detailed histologic diagnoses, allowing classification of cancer deaths, have only been available since 1967. For the 76 cancer deaths reported in 1967-73 in Eskimos living in that region, we calculated the observed and expected rates (based on figures reported for all Canadians in 1968-72) for various cancer types for both sexes. Results The 180 histologically proved cases of neoplastic disease in NWT Eskimos in 1949-74 are listed in Table I in order of frequency. Lung cancer leads the list overall but cervical cancer (including in situ cases) was the most frequent type of cancer in women. The high frequency of salivary gland cancers has been previously noted. Nasopharyngeal cancer is also common, particularly in men, in whom it equals bronchogenic carcinoma in frequency. The age-adjusted cancer mortality rates in Eskimos for Table
II.Age-adjusted mortality
rates for all Canadians in 1968-72
Site of
primary tumour*
rates of various
(expected) Total of
Age
malignant
*No cases were detected in 1949. flncluding one Wilms' tumour and one fibrosarcoma. JFive tumours originated in the ampulla of Vater and only two in the
gallbladder. of §0ne case each cancer of the skin, lip, thyroid, vulva and ovary; one choriocarcinoma.
tumours in NWT Eskimos in 1967-73
(observed), compared with Females
Males
no.
group (yr)
cases
Observed
Expected
7 5 12 1 7 8 2 1 3 3 2 1 2
1 2 3 2 0
*0ne case each of cancer of the stomach (0/E 0.35), prostate (0/E 0.42) and testis (0/E primary in two men and one woman. tSignificant at PP
Summary: The records of the two main referral centres for the western and central Arctic were reviewed for Eskimo patients with cancer diagnosed between 1949 and 1974 inclusive. To these were added the records for the past 6 years of patients from the eastern Arctic, giving a total of 180 histologically proved cases of malignant disease. The data were analysed for prevalence, relative frequency, geographic distribution and changes with time of the various neoplasms. Salivary gland and renal neoplasms have in recent years been displaced by cancer of the lung and uterine cervix as the most common malignant tumours in Canadian Eskimos. The prevalence of lung cancer in Eskimo women, particularly of the central Arctic, is striking. Cancer of the nasopharynx kept the same relative position during early and late years of the survey period. Breast cancer is still uncommon in Eskimos. Lactation rather than gestation history appeared to be an important protective factor. Cases of cervical cancer outnumbered those of breast cancer by 18 to 4, in sharp contrast to the relative proportions of these tumours in all Canadian women. Resume: Les changements dans les types de neoplasmes chez des Esquimaux canadiens Nous
avons
passe
en revue
les dossiers des malades
Esquimaux qui avaient ete envoyes aux deux centres specialises de I'Arctique occidental et central pour des cas de cancer, diagnostiques de 1949 a 1974 inclusivement. A ces cas sont venus s'ajouter les dossiers des malades referes pendant les 6 dernieres annees de I'Arctique oriental. Nous avions ainsi un total de 180 cas de tumeurs malignes, dont la nature etait demontree par histologie. Ces donnees ont ete analyses, du point de vue de la predominance, de la frequence relative, de la distribution geographique et des changements avec le temps des divers neoplasmes. Au cours des dernieres annees les neoplasmes des glandes salivaires et des reins ont ete remplaces par unit, northern region medical Canada, Charles Camsell Hospital, Edmonton; tnorthern medical unit, University of Manitoba, Winnipeg; and JThe Montreal General Hospital Reprint requests to: Dr. O. Schaefer, Northern medical research unit, Charles Camsell Hospital, 12815-115 Ave., Edmonton, Alta. T5M 3A4 From *the northern medical research services branch, Health and Welfare
un cancer des poumons et du col uterin qui sont devenus les tumeurs malignes les plus courantes chez les Esquimaux du Canada. La predominance du cancer pulmonaire chez les femmes Esquimaudes, surtout celles de I'Arctique central, est un fait particulierement frappant. Le cancer du nasopharynx a conserve la meme frequence relative pendant les deux periodes couvrant I'enquete. Chez les Esquimaux le cancer mammaire est encore tres rare. C'est I'allaitement maternal plus que le developpement de la grossesse qui nous parait etre le facteur protecteur essentiel. Le cas du cancer cervical depassent en nombre ceux du cancer mammaire dans la proportion de 18 a 4, ce qui contraste considerablement avec les proportions relatives de ces tumeurs pour I'ensemble de toutes les femmes Canadiennes.
Eskimos
were
probably
at no time free from
neoplastic
earlier Canadian medical1'2 and nonmedical3 observers. Fibiger4 in 1923 reported 14 cases of malignant disease diagnosed over a 10-year period in native Greenlanders, but the an¬ cestry of this group is partially European. For the next few decades the occurrence of tumours in apparently pureblooded Eskimos was considered rare enough to warrant publication of single case reports one of a "pure" Greenlandic Eskimo5 and one of a Canadian Eskimo.6 However, malignant disease was found at autopsy in 15 of 57 Alaskan Eskimos in 1956-58,7 in 11 of 90 Canadian Eskimos in 1951-608 and in 47 of 250 Eskimos and Aleuts in 1959-68.* Fortuine10 reviewed the data on 85 tumours diagnosed in southwest Alaskan Eskimos during 1957-67 in their main hospital and referral centre at Bethel and found, as did Hurst11 in an earlier report of 76 cases of malignant disease diagnosed over a 6-year period among all Alaskan Eskimos, a high prevalence of esophageal cancer. In Canada Schaefer1213 and Wallace and colleagues14 stressed the pre¬ valence of salivary gland tumours and the rarity of breast cancer15 in Eskimos. The present review draws attention to a remarkable change in the prevalence pattern of neoplastic disease ob¬ served over a 25-year period in Canadian Eskimos from different geographic areas with varying duration and in¬ tensity of acculturation.
disease, although this has been suggested by
some
CMA JOURNAL/JUNE 21, 1975/VOL. 112 1399
Material and methods
Patient records
were
reviewed in Charles Camsell Hos¬
pital and Dr. W.W. Cross Cancer Institute in Edmonton, and in the Health Sciences Centre, St. Boniface General Hospital and the Provincial Cancer Registry in Winnipeg. For these two centres we had confidence in the completeness of the review back to 1949, by which time a regular and persisting pattern of referral from the western and
central Arctic had been established. In a survey of the eastern Arctic the records of The Montreal General Hos¬ pital and sanatoria in Hamilton and Toronto were searched for histologically verified cases of neoplastic disease in Eskimos. For these referral centres it was not possible to be confident of the completeness of the survey for the years before 1967. Also, up to 1960 the eastern Arctic was less accessible to medical screening and evacuation of pa¬ tients; since then, regular services have operated. If our numbers are in error they are too low: at least a few patients probably died in the Arctic before their condition
the 7-year period 1967-73 are compared in Table II with those for all Canadians in the 5-year period 1968-72. The observed mortality exceeded significantly the expected rate for lung cancer in males and in females, for nasopharyngeal cancer in males and for salivary gland cancer in the two sexes considered together. For cancer of the ampulla of Vater, esophageal cancer and hepatoma the observed morTable I.Anatomic sites of 180 neoplasms in Eskimos of the Northwest Territories, proved histologically in Edmonton, Winnipeg, Montreal and Toronto in 1950-74*
diagnosed. Although we have included in the overall figures the 34 cases in eastern Arctic Eskimos the discussion of the chang¬ ing pattern of neoplastic disease in Eskimos is limited to was
the 146 cases in western and central Arctic Eskimos. We reviewed also the death certificates for the Northwest Territories from 1960, but detailed histologic diagnoses, allowing classification of cancer deaths, have only been available since 1967. For the 76 cancer deaths reported in 1967-73 in Eskimos living in that region, we calculated the observed and expected rates (based on figures reported for all Canadians in 1968-72) for various cancer types for both sexes. Results The 180 histologically proved cases of neoplastic disease in NWT Eskimos in 1949-74 are listed in Table I in order of frequency. Lung cancer leads the list overall but cervical cancer (including in situ cases) was the most frequent type of cancer in women. The high frequency of salivary gland cancers has been previously noted. Nasopharyngeal cancer is also common, particularly in men, in whom it equals bronchogenic carcinoma in frequency. The age-adjusted cancer mortality rates in Eskimos for Table
II.Age-adjusted mortality
rates for all Canadians in 1968-72
Site of
primary tumour*
rates of various
(expected) Total of
Age
malignant
*No cases were detected in 1949. flncluding one Wilms' tumour and one fibrosarcoma. JFive tumours originated in the ampulla of Vater and only two in the
gallbladder. of §0ne case each cancer of the skin, lip, thyroid, vulva and ovary; one choriocarcinoma.
tumours in NWT Eskimos in 1967-73
(observed), compared with Females
Males
no.
group (yr)
cases
Observed
Expected
7 5 12 1 7 8 2 1 3 3 2 1 2
1 2 3 2 0
*0ne case each of cancer of the stomach (0/E 0.35), prostate (0/E 0.42) and testis (0/E primary in two men and one woman. tSignificant at PP
