BETHESDA, Maryland—Researchers have begun accruing 32,400 men for a long-term prostate cancer study that will test whether selenium(Drug information on selenium) and/or vitamin E can prevent the disease. The Southwest Oncology Group (SWOG) will coordinate the Selenium and Vitamin E(Drug information on vitamin e) Cancer Trial (SELECT) at more than 400 sites in the United States, Canada, and Puerto Rico. Participants will be followed for up to 12 years.
"SELECT is the first study designed to look specifically at the effects of vitamin E and selenium, both separately and together, in preventing prostate cancer," the National Cancer Institute (NCI) said in announcing the trial’s opening.
Selenium and vitamin E are antioxidants. The postulated mechanism for any protective benefit is the ability of antioxidants to neutralize free radicals and thus prevent genetic damage to cells that could lead to cancer.
Evidence that supplements of the two nutrients might help protect men against prostate cancer emerged from two prevention studies reported in the mid- and late 1990s. A study of selenium supplementation in 1,000 men and women found that it did not reduce nonmelanoma skin cancer. However, male participants had a reduction in incidence of prostate cancer of more than 60%.
Similarly, a Finnish study of 29,000 male smokers found that neither vitamin E nor beta-carotene reduced their risk of lung cancer, and, in fact, those taking beta-carotene were more apt to develop and die of the disease. However, the men who got vitamin E had a reduction in prostate cancer incidence of 32%.
"Because these trials were not designed with prostate cancer as their primary endpoint, the SELECT trial has been designed to answer the question definitively," said Charles Coltman, Jr., MD, director of the San Antonio Cancer Institute and chairman of SWOG.
Prostate cancer will strike some 198,100 American men during 2001 and cause 31,500 deaths. "These statistics give us a glimpse of the important impact prostate cancer prevention could have on the lives of men of all ages, but most critically black men, who are at the highest risk," Dr. Coltman said.
