UTHSC enrolls men in largest-ever prostate cancer prevention trialVitamin E and selenium to be tested as prevention agents
Healthy men 55 and older are needed for the largest-ever prostate cancer prevention study, recently launched by the National Cancer Institute (NCI) and the Health Science Center. The university is part of a network of research sites known as the Southwest Oncology Group (SWOG). The Selenium and Vitamin E Cancer Prevention Trial, or SELECT, seeks to learn if these two dietary supplements can protect against prostate cancer, which in men is the most common form of cancer after skin cancer.
More than 400 sites in the United States, Puerto Rico and Canada are recruiting participants for SELECT, which will take up to 12 years to complete. The study will enroll a total of 32,400 men, including 500 at the Health Science Center.
"SELECT is the first study designed to look directly at the effects of vitamin E and selenium, both separately and together, in preventing prostate cancer," said Dr. Joseph W. Basler, associate professor of surgery at the Health Science Center and the principal investigator for the San Antonio portion of the study. "Previous research involving vitamin E and selenium suggested that these nutrients might prevent prostate cancer, but we don't know for sure. When SELECT is finished we will know whether these supplements can prevent prostate cancer."
During this year alone, prostate cancer will be diagnosed in about 198,100 Americans and more than 31,500 men are expected to die of the disease. In Texas, 12,500 men will get prostate cancer and 2,000 men will die of it. Risk factors for the disease include being over age 55, being black, or having a father or brother with prostate cancer.
"It is crucial that men of all races and ethnic backgrounds participate in SELECT," said Leslie Ford, M.D., associate director for clinical research in NCI's Division of Cancer Prevention. "And since African-American men have the highest incidence of prostate cancer in the world, we especially encourage them to consider joining this trial." The disease also strikes black men at a younger age, so they will be eligible to enroll in the study at age 50, vs. age 55 for other racial and ethnic groups. There is no upper age limit for participation in SELECT.
"We are looking for quite a few good men to join SELECT," said Dr. Charles A. Coltman Jr., chairman of SWOG, professor of medicine at the Health Science Center and director of the San Antonio Cancer Institute, which is a partnership between the Health Science Center and the Cancer Therapy & Research Center. "This study is important for the men who join, not only because they might prevent prostate cancer for themselves, but also because what we learn has the potential to benefit future generations of men."
Selenium and vitamin E, both naturally occurring nutrients, are anti-oxidants. They are capable of neutralizing toxins known as "free radicals" that might otherwise damage the genetic material of cells and possibly lead to cancer. These nutrients were chosen for study because of the results of two other large cancer prevention trials.
In a study of selenium to prevent one type of non-melanoma skin cancer in 1,000 men and women, reported in 1996, investigators found that while the supplement did not reduce skin cancer, it did decrease the incidence of prostate cancer in men by more than 60 percent.
In another trial, published in 1998, beta-carotene and vitamin E were tested to prevent lung cancer in 29,000 Finnish men who smoked. Those who took vitamin E had 32 percent less prostate cancer. Neither beta-carotene nor vitamin E prevented lung cancer. In fact, the men who smoked and took beta-carotene were more apt to get lung cancer and die from it than men who did not take this supplement.
"SELECT is the critical next step for pursuing the promising leads we saw for the prevention of prostate cancer," said Dr. Ford, who is responsible for all aspects of NCI's involvement in SELECT. "The only way to determine the real value of these supplements for prostate cancer is to do a large clinical trial focused specifically on this disease." Study investigators hope to recruit all the study participants during the first five years of the trial, so that each man can be followed for at least seven years.
Men in the study from South and Central Texas will visit the Health Science Center once every six months. Upon enrollment, they will be assigned by chance to one of four groups. One group will take 200 micrograms of selenium daily plus an inactive capsule, or placebo, that looks like vitamin E. Another group will take 400 milligrams of vitamin E daily along with a placebo that looks like selenium. A third group will take both selenium and vitamin E. The final group will be given two placebos.
Men who join SELECT will not need to change their diet in any way, but they must stop taking any supplements they buy themselves that contain selenium or vitamin E. If participants wish to take a multivitamin, SWOG will provide, without charge, a specially formulated one that does not contain selenium or vitamin E.
Men may be able to participate in SELECT if they are 55 or older (50 or older for black men) and have not had prostate cancer. Participants also must not have had any other cancer, except non-melanoma skin cancer, in the last five years and must generally be in good health.
Men interested in joining the study may call the Health Science Center's division of urology at ext. 7-0214. Dr. Ian M. Thompson, professor of surgery and chief of the division, is one of the national co-principal investigators for this study.
For more information about the study or prostate cancer, call the National Cancer Institute's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). Information is available in English or Spanish. The number for callers with TTY equipment is 1-800-332-8615. Visit NCI's Web site at http://cancer.gov/ select or visit SWOG's Web site at http://swog.org and choose SELECT.
Four pharmaceutical companies are providing selenium and vitamin E capsules and multivitamins for the study: Roche Vitamins Inc., Parsipanny, N.J.; Sabinsa Corp., Piscataway, N.J.; Nutricia Manufacturing USA Inc., Greenville, S.C.; and BioAdvantex Pharma Inc., Mississauga, Ontario, Canada.