Cancer incidence and mortality in Ontario First Nations, 1968-1991 (Canada)

Objective: To determine cancer incidence and mortality rates in Ontario First Nations (FN) people (native Indians) during 1968-1991 and to compare these with rates in the Ontario population. Methods: A cohort of 141,290 Ontario FN was created from registration files maintained by the Canadian government. Cancers and deaths were ascertained by linkage to the provincial cancer registry and mortality file, which also provided general population comparison data. Results: Cancer incidence was significantly lower in FN compared to the general population for all cancer (rate ratio (RR) = 0.72 for females; 0.62 for males), breast cancer (RR = 0.54), lung cancer in men (RR = 0.68), prostate cancer (RR = 0.57) and colorectal cancer (RR = 0.58 and 0.57 in men and women, respectively). Rates were significantly higher in FN for cervical cancer (RR = 1.73) and gallbladder cancer (2.05 and 2.20 in men and women, respectively). Incidence rates increased significantly in FN people between 1968-1975 and 1984-1991 for all cancer and for the major cancers (breast, lung, prostate and colorectal). Colorectal cancer rate ratios were significantly higher in 1984-1991 than in 1968-1975, indicating converging incidence rates. Patterns of cancer mortality were similar. Conclusions: These trends are compatible with a population in epidemiologic transition to the Euro-American disease pattern which is dominated by chronic diseases.