HOUSTON, TEXAS. It is estimated that 230,000 American men will be diagnosed with prostate cancer and that 30,000 men will die from the disease in 2004. There are currently no pharmaceutical drugs that have been proven effective in preventing prostate cancer. Finasteride (Proscar) showed some promise in reducing overall cancer incidence but was, unfortunately, associated with a significant increase in advanced cancers. Finasteride is therefore no longer considered suitable for prostate cancer prevention.
In contrast, two natural agents, selenium and vitamin E, have been found effective in prostate cancer prevention. The Nutritional Prevention of Cancer (NPC) study concluded that supplementing with 200 micrograms/day of elemental selenium (in the form of high-selenium yeast) reduced prostate cancer risk by 63%. The large Finnish ATBC study concluded that supplementing with 50 mg/day (50 IU/day) of synthetic alpha-tocopheryl-acetate reduced prostate cancer risk and mortality by 32% and 41% respectively.
Based on these and other findings, the National Cancer Institute has embarked upon a major trial, the
Selenium and Vitamin E Cancer Prevention Trial (SELECT). The trial, opened for recruitment in July 2001,
now has a total enrollment of 35,534 men with a median age of 62 years (range of 50-93 years) who were
free of prostate cancer. The expected follow-up time is 7-12 years. After much deliberation and a thorough
review of the literature, the SELECT Steering Committee decided that the supplements to be evaluated
would be 200 micrograms/day of elemental selenium in the form of L-selenomethionine and 400 IU/day of
synthetic alpha-tocopheryl acetate. The trial design will involve 5 pair-wise comparisons of prostate cancer
incidence, in association with – vitamin E vs placebo, selenium vs placebo, vitamin E plus selenium
(combination) vs placebo, combination vs vitamin E, and combination vs selenium. The Steering Committee
points out that there is strong evidence that 200 micrograms/day of elemental selenium is entirely safe, as is
up to 1000 mg/day of vitamin E. They acknowledge that natural alpha-tocopherol is significantly more
effective than synthetic alpha-tocopheryl acetate and that gamma-tocopherol may be even more effective
than either as far as prostate cancer prevention is concerned. However, due to the fact that more clinical
trial data is available on synthetic alpha-tocopheryl acetate they decided to go ahead with this form. All
study participants will also receive a daily multivitamin devoid of selenium and vitamin E, but including 400
IU of vitamin D3.
Editor’s comment: It is indeed gratifying to see such a massive undertaking by the National Cancer Institute aimed at evaluating natural supplements in the prevention of prostate cancer. Personally, I would have liked to see the vitamin E component consist of a 50:50 mixture of natural alpha- and gamma- tocopherols, but the Steering Committee obviously decided that there was not enough evidence to support this. In any case, involving over 35,000 men in a 7- to 12-year trial of selenium and vitamin E clearly shows that hopes are high that these two natural compounds will prove effective in prostate cancer prevention and that they are entirely safe. In view of this, I see no reason to wait 10 or more years for the results to be published. All men should supplement with selenomethionine and natural vitamin E (preferably a 50:50 mixture of alpha- and gamma-tocopherols).