IS LOW SELENIUM STATUS A RISK FACTOR FOR LUNG-CANCER

The hypothesis that low selenium may in some circumstances be a risk f actor for lung cancer was investigated in a case-control study nested within a longitudinal study. Serum samples from 9, 101 cancer-free ind ividuals were collected and stored at -20 degrees C by the Finnish Mob ile Clinic in 1968-1971 and 1973-1976, During follow-up until the end of 1991, 95 cases of lung cancer were diagnosed. Selenium concentratio ns were determined from the serum samples of the cases and 190 control s, individually matched for sex, age, and place of residence. Mean lev els of serum selenium in cases and controls were 53.2 mu g/liter and 5 7.8 mu g/liter, respectively. The relative risk of lung cancer between the highest and lowest tertiles of serum selenium, adjusted for smoki ng, serum alpha-tocopherol, serum cholesterol, serum copper, serum oro somucoid, and body mass index (kg/m(2)), was 0.41 (95% confidence inte rval (CI) 0.17-0.94). The association was stronger at lower levels (<5 .9 mg/liter) of alpha-tocopherol (relative risk = 0.24, 95% CI 0.07-0. 85), The association was also pronounced among current smokers and at higher levels of serum orosomucoid and serum copper. The relative risk for smokers who were twice ranked in higher selenium tertiles, at an interval of 4-7 years, in comparison with smokers who remained in the lowest tertile was 0.16 (95% CI 0.04-0.74), In accordance with the hyp othesis, the findings suggest that very low selenium status may contri bute to the risk of lung cancer.