Toenail selenium and breast cancer - a case-control study in Finland

Objective: Low. levels of selenium have been associated with a higher risk of cardiovascular diseases and cancer ill humans. Since 1984. selenium supp lementation through fertilizers has been employed in Finland to increase th e very low concentration of selenium in the nation's food supply, As a resu lt, the selenium concentration of Finnish foods became one of the highest i n Europe. A decode after selenium supplementation began, the association be tween toenail selenium and the risk of breast cancer was examined. Design: Case-control study. Setting: Eastern Finland. Subjects: 289 pre- and postmenopausal bl east cancer cases and 433 communit y controls. The diagnosis was unknown at the time the tot nail samples were collected. Results: The mean toenail selenium concentration was 0.80 mg/kg in premenop ausal cases and 0.84 mg/kg in premenopausal controls: and 0.77 mg/kg in pos tmenopausal cases and 0.80 mg/kg in postmenopausal controls. The odds ratio (OR) comparing the highest with the lowest quintiles of toenail selenium c oncentration was 1.1 (95% CI 0.4-3.2) in premenopausal women and 0.7 (95% C I 0.3-1.5) in postmenopausal women. The intake of retinol. beta-carotene, v itamin E: and vitamin C did not change the association between toenail sele nium and breast cancer. Conclusions: A decade after selenium supplementation. selenium scents not t o be an important factor in the etiology of breast cancer, neither in preme nopausal nor postmenopausal women. Sponsorship: This work was supported by the EVO funds from the Kuopio Unive rsity Hospital and by research grants from the Academy of Finland, Yrjo, Ja hnsson Foundation and Juho Vainio Foundation.