Cancer in the Sami population of North Norway, 1970-1997.

The Sami population in North Norway constitutes an ethnic minority with a lifestyle that diverges from that of the rest of the population. A cohort of 19 801 people of Sami origin was followed for cancer incidence over the period 1970-1997 by the Norwegian Cancer Registry. Among the Sami 1340 cases of cancer were observed versus 1658.2 expected, based on a regional reference population. For both sexes a significantly decreased incidence of colon cancer was observed. The standardized incidence ratio (SIR) for men was 0.50 (95% confidence interval (CI) 0.34-0.71) and for women 0.62 (95% CI 0.43-0.85). Low SIRs were observed for lung cancer: 0.63 (95% CI 0.51-0.77) and 0.60 (95% CI 0.37-0.91), for men and women, respectively. Men of Sami ancestry had a decreased risk of prostate cancer: SIR 0.57 (95% CI 0.45-0.71). Among women 127 cases of breast cancer were observed versus 149.6 expected. A relatively high physical activity and a diet rich in fish may in part explain the low cancer incidence. Some Sami were exposed to radioactivity as a result of their diet based on reindeer products. Adverse effects on their cancer incidence were not observed.