The National Cancer Institute has launched its largest-ever prevention study to learn if two common dietary supplements can reduce men's risk of prostate cancer.

The Selenium and Vitamin E Cancer Prevention Trial is based in large part on previous research conducted at the Arizona Cancer Center, which will be one of more than 400 sites participating in the trial.

Researchers hope to enroll 32,000 healthy men 55 and older to see if taking a daily dose of selenium or vitamin E, or the two combined, offers significant protection from prostate cancer. The Arizona Cancer Center, at the University of Arizona, is seeking 500 men from Southern Arizona to take part.

The minimum age is 50 for black men, who have a much higher incidence of prostate cancer, and are two to three times as likely to die from it, as other men.

The 12-year study will be conducted at more than 400 sites in the United States, Canada and Puerto Rico.

After skin cancer, prostate cancer is the most widely diagnosed cancer in this country, where more than 198,000 new cases will be discovered this year, according to the American Cancer Society.

It will kill 31,500 American men this year, making it the nation's No. 3 cancer killer, behind lung cancer in men and women and breast cancer in women.

In Arizona, 3,600 men will be diagnosed with prostate cancer and 600 will die from it this year, according to the Arizona Cancer Center.

Selenium and vitamin E are naturally occurring nutrients that protect normal cells from the kind of genetic damage that can lead to some cancers.

A 1996 Arizona Cancer Center study - headed by Larry C. Clark, a researcher who died last year from prostate cancer - indicated selenium decreased prostate cancer incidence by 60 percent. The result was considered promising but not definitive, since the study was designed to determine selenium's ability to prevent skin cancer and the prostate cancer finding was accidental.

The Selenium and Vitamin E Cancer Prevention Trial, called the SELECT trial, also follows a 1998 Finnish study of vitamin E's ability to prevent lung cancer in smokers, which had the same sort of result as Clark's study. The vitamin E did nothing to prevent lung cancer, but the men who took it had 32 percent fewer cases of prostate cancer than those who did not.

"Right now, these are two of the best leads we have," said Dr. Frederick Ahmann, a prostate cancer specialist with the Arizona Cancer Center.

Richard Cavelli, a patient of Ahmann's, was diagnosed with prostate cancer six years ago and so is ineligible for the trial. But Cavelli said Tuesday that he plans to encourage his friends to take part in the study.

"I have two sons and I figure the study will help them, and others," said Cavelli, 62.

Dr. Leslie Ford, associate director of cancer prevention for the National Cancer Institute, emphasized the importance of black men enrolling in the trial.

"Since African-American men have the highest incidence of prostate cancer in the world, we especially encourage them to consider joining this trial," Ford said.

Men who enroll in the study will be randomly assigned to one of four treatments: two capsules daily of selenium, two of vitamin E, one capsule of each supplement or two capsules of an inactive placebo drug. Participants will take their study drug for five years and be followed by doctors conducting the study for up to 12 years.

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There is no cost to participants, and the health benefits are significant, Ahmann and other researchers involved with the study said Tuesday.

Every man enrolled in the study will get a free annual examination, including a digital rectal exam and a PSA - prostate specific antigen - blood test.

Researchers emphasized Tuesday that the SELECT trial is low-risk, involving two well-known nutritional supplements.

Recent reports of the death of a young woman taking part in an asthma drug study at Johns Hopkins University in Baltimore should not discourage anyone from enrolling in the SELECT trial, said Laurie Young, director of development and communication at the Arizona Cancer Center.

"People shouldn't be concerned," Young said, "because both of the nutritional supplements being studied have been used worldwide in studies with no significant toxicities. Also, they are both available over-the-counter and have been well-tolerated in thousands of individuals."

But that should not encourage men to put themselves on selenium or vitamin E, rather than enroll in the study, Ahmann said.

"If they don't enroll in the trial, then we lose information that could benefit them and others," Ahmann said.

The Selenium and Vitamin E Cancer Prevention Trial is the third large-scale prevention study conducted by the National Cancer Institute over the last decade.

The Breast Cancer Prevention Trial, begun in 1992, enrolled 13,000 women and found that the breast cancer drug tamoxifen can prevent the disease in healthy women at high risk of developing breast cancer.

The first Prostate Cancer Prevention Trial, begun in 1993, enrolled 18,000 men to test whether the drug Proscar, used to treat prostate disease, can prevent prostate cancer. Results are not yet known.

The ongoing Study of Tamoxifen and Raloxifene will enroll 22,000 women to see which of the two drugs can reduce breast cancer risk most effectively with the least side effects.

From Healthy.net