HELSINKI, Finland--Supplemental vitamin E significantly decreased both the incidence and mortality of prostate cancer in a large randomized trial of male smokers in Finland, said Olli P. Heinonen, MD, DSc, and his colleagues from the University of Helsinki, the National Cancer Institute, and Montefiore Medical Center, New York.
The study was part of a randomized, placebo-controlled cancer prevention trial designed to determine whether supplemental vitamin E (alpha-tocopherol) and/or vitamin A (beta-carotene) could reduce the incidence of lung cancer. The study included 29,133 male smokers, aged 50 to 69 years, residing in Finland.
Participants were assigned to one of four groups--vitamin E (50 mg/day) alone, vitamin A (20 mg/day) alone, both vitamins, or placebo. After 5 to 8 years (median, 6.1), the researchers found 246 new cases of prostate cancer and 62 deaths from the disease. The incidence was 32% lower among those who received vitamin E (alone or with vitamin A), and mortality was 41% lower.
The reduction was seen in the number of cases of prostate cancer diagnosed clinically but not in the number of latent cases detected unexpectedly during clinical examination or at autopsy in men who died from other causes.
"A reduction in clinically overt cancers appeared soon after the onset of supplementation, suggesting that alpha-tocopherol influences the transformation phase of cancer from latent to clinical," the researchers said (J Natl Cancer Inst 90:440-446, 1998). Vitamin A alone did not reduce prostate cancer incidence or mortality; in fact, there was a trend toward increased incidence and mortality among those receiving vitamin A alone.