Low plasma selenium as a risk factor for cancer death in middle-aged men.

In a population study, 10,000 men (aged 46-48 years) were invited to a health screening program. At follow-up, which was up to eight years later, 61 subjects had died from cancer; from 35 of these subjects, plasma samples were available that were obtained at the initial screening. These samples, together with samples from two living controls for each case, were analyzed for selenium, retinol, cholesterol, triglyceride, and a number of plasma proteins. Plasma selenium was significantly lower (p less than 0.05) in cases than in controls (means: 1.06 vs. 1.12 mumol/l). The proportion of cases increased significantly from the highest to the lowest quintile of plasma selenium, and the relative risk for cancer death was 3.8 times higher in the lowest quintile compared with the highest. Mean plasma retinol was similar in cases (2.53 mumol/l) and controls (2.56 mumol/l). Cases and controls also had similar values for plasma cholesterol, triglyceride, uric acid, apolipoprotein B, orosomucoid, prealbumin, retinol-binding protein, and beta 2-microglobulin. Apolipoprotein AI in plasma was lower among cases (p less than 0.025). Cases smoked significantly more than controls did (p less than 0.05). Data indicate that low plasma selenium was a risk factor for cancer death in middle-aged men who lived in the same area. Further studies are necessary to establish whether differences in selenium intake, selenium metabolism, or other factors related to selenium are responsible for the relations observed. At present, the available data do not justify selenium supplementation programs in the whole population.