Cancer incidence among Sami in Northern Finland, 1979-1998.

Abstract

The Sami population living in Northern Finland represents a specific genetic background and a way of life that is different from other Finns. A cohort of 2,100 Sami and 4,174 non-Sami people from the 2 northernmost municipalities of Finland on 31 December 1978 was identified from the national Population Register and followed up through the Finnish Cancer Registry for cancer incidence during 1979-1998. There were 111 cancer cases among the Sami, while the expected number based on the average cancer incidence in the Finnish population was 173. Among the non-Sami cohort members, there were 226 cases of cancer vs. 224 expected cases. The Sami had significantly decreased incidence of cancers of the prostate [standardised incidence ratio (SIR) 0.25; 95% confidence interval (CI) 0.08-0.58] and breast (SIR 0.36; 95% CI 0.14-0.73), similarly for both localised and nonlocalised tumours. Low SIRs were also observed for bladder cancer (SIR 0.28; 97% CI 0.03-0.99) basal cell carcinoma of the skin (SIR 0.12; 95% CI 0.03-0.30) and other nonmelanoma skin cancers (SIR 0; 95% CI 0-0.63). In contrast to other subcategories of the Sami, the Skolts, whose lifestyle stems from areas that now belong to Russia, showed a nonreduced overall cancer risk and a significantly elevated risk for stomach cancer (SIR 3.8; 95% CI 1.5-7.8). The low cancer incidence among the other Sami populations in Finland cannot be fully explained by their specific way of life. It seems likely that the Sami ethnicity carries a reduced cancer incidence level. Although many Sami have been exposed to radioactive fallout from the nuclear weapon tests via their reindeer-rich diet, this does not seem to affect their cancer risk.