The changing picture of neoplastic disease in the western and central Canadian Arctic (1950-1980).

Data on 239 verified cases of malignant disease diagnosed from January 1950 through December 1980 in 104 male and 135 female Inuit from the western and central Canadian Arctic were reviewed. Tumours of the salivary glands, kidney and nasopharynx were the most frequent between 1950 and 1966, but their frequency declined thereafter. The most frequent tumours in the most recent period studied were lung, cervical and colorectal cancers. Breast cancer was absent before 1966 and was found in only 2 of 107 Canadian Inuit women stricken with cancer from 1967 to 1980, whereas the recent rates in the longer-acculturated Inuit of Alaska and Greenland have approached those prevailing in modern Western women. The Inuit appeared to be more prone than other North Americans to cancer of the esophagus, liver and ampulla of Vater but less prone to cancer of the skin, prostate, pancreas and stomach. The gradual reduction in the relative frequency of tumours typical for traditional Inuit and their replacement by "modern" tumours appear to reflect the history of local acculturation. Various factors in the environment, nutritional habits and lifestyle may contribute to the unusual and changing epidemiologic patterns of cancer in Canadian Inuit.