More than 35,500 men have volunteered to take part in the largest-ever prostate-cancer prevention study, known as the Selenium and Vitamin E Cancer Prevention Trial (SELECT), in which the center plays a key role. The study seeks to determine whether vitamin E and the trace element selenium can protect against prostate cancer, the most common form of malignancy in men excluding non-melanoma skin cancer.
After surpassing their goal of 32,400 participants, recruitment for the study ended last month, two years earlier than anticipated. About 15 percent of participants are African American men, who have the highest incidence of prostate cancer and the poorest survival rates. That percentage is much higher than has been attained by other cancer-prevention studies, said Phyllis Goodman, the project's lead statistician and an investigator in the Public Health Sciences Division.
"The percentage of African-American participants in previous prostate-cancer prevention studies has been in the single digits," she said. "Our success was due to a lot of community outreach, including partnering with African-American organizations and churches."
The Public Health Sciences Division oversees the statistical analysis for the $180 million, National Cancer Institute-funded study, which involves 427 clinical sites around the country, including four Seattle-area hospitals. Cancer Research And Biostatistics (CRAB), a Seattle nonprofit organization with close ties to Fred Hutchinson, leads the data coordination and computational analysis for the project. Dr. John Crowley, chief executive officer of CRAB and a PHS investigator, is the principal investigator for the SELECT Statistical Center.
Men enrolled in the study visit their local study sites once every six months for a minimum of seven years. Each year the men have a limited physical exam, which includes a suggested digital rectal exam and prostate-specific antigen (PSA) test.
Upon enrollment, the men were assigned by chance to one of four groups. One group takes 200 micrograms of selenium daily plus an inactive capsule, or placebo, that looks like vitamin E. Another group takes 400 IU (international units) of vitamin E daily along with a placebo that looks like selenium. A third group takes both selenium and vitamin E. The final group is given two placebos. Neither the men nor the investigators know which preparation the men are receiving until the follow-up period is complete. Researchers will monitor the number of prostate-cancer cases that develop among the participants to assess whether vitamin E and/or selenium are associated with a difference in prostate-cancer incidence.
Since recruitment began in 2001, three ancillary studies have been added that will investigate the effects of vitamin E and selenium on other health issues in the SELECT participants, Goodman said. These additional studies are done in cooperation with the SELECT researchers and Statistical Center. The studies are funded by other NIH institutes and represent a collaborative model that is encouraged by the NIH.
One study led by researchers at the University of Kentucky, which will involve 5,000 of the SELECT participants, seeks to determine whether vitamin E and selenium can reduce the incidence of Alzheimer's disease. Previous research has suggested that these antioxidants may protect against the condition.
A second study led by investigators at Harvard Medical School will assess whether vitamin E and selenium can reduce the risk of visually significant macular degeneration and cataracts, two conditions that can lead to vision loss.
The third ancillary study, led by Cornell University, will examine the role of vitamin E and selenium in chronic obstructive pulmonary disease, a smoking-related disease in which lung function is decreased.
A fourth study—due to be launched by researchers at the University of Arizona—will investigate whether vitamin E and selenium can reduce the risk of benign colorectal tumors known as adenomas, which can lead to cancer.