Finnish researchers at the National Public Health Institute report that a low selenium intake is associated with an increased risk of lung cancer. Their study involved over 9000 cancer-free individuals who had blood samples taken as part of the 1968-1971 Finnish Mobile Clinic Health Examination Survey. During the follow-up period until the end of 1991 95 of the study participants were diagnosed with lung cancer. These cases were matched with 190 controls for sex, age, and place of residence. The researchers found that individuals with selenium serum levels below 45.5 micrograms/liter had more than twice the risk of developing lung cancer than did participants with levels above 60.6 micrograms/liter. This association held true even when adjusting for smoking status. Smoking, of course, was found to be a potent risk factor for lung cancer with current smokers having a four-fold increase in risk as compared to non-smokers. A selenium deficiency was found to be particularly detrimental if combined with a low serum level of vitamin E (alpha-tocopherol). Study participants who had both low selenium and low vitamin E levels (selenium less than 45.5 micrograms/liter and alpha-tocopherol less than 5.9 micrograms/liter) had a four times higher risk of lung cancer than did individuals with selenium levels at or above 45.5 micrograms/liter and vitamin E levels at or above 5.9 micrograms/liter. The researchers also noted that high levels of copper in the blood were associated with an increased lung cancer risk. They conclude that a low selenium level may be an important risk factor for lung cancer especially among smokers and people with low vitamin E intakes.
Knekt, Paul, et al. Is low selenium status a risk factor for lung cancer? American Journal of Epidemiology, Vol. 148, November 15, 1998, pp. 975-82