Healthy men age 55 and older are needed for the largest-ever prostate cancer prevention study, launched by the National Cancer Institute (NCI) and a network of researchers known as the Southwest Oncology Group (SWOG). The Selenium and Vitamin E Cancer Prevention Trial, or SELECT, will determine if these two dietary supplements can protect against prostate cancer, the most common form of cancer after skin cancer, in men. The study will include approximately 32,000 men.

Selenium and vitamin E, both naturally occurring nutrients, are antioxidants. 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.

Men may be able to participate in SELECT if they:

are age 55 or older (age 50 or older for black men);

have never had prostate cancer and have not had any other cancer, except nonmelanoma skin cancer, in the last five years;

are generally in good health.