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Name of the Trial

Phase III Randomized Study of Selenium in Patients with Adenomatous Colorectal Polyps (UARIZ-00-0430-01). See the protocol summary ³.

Principal Investigator

Dr. M. Peter Lance Principal Investigator

Dr. M. Peter Lance, Arizona Cancer Center at University of Arizona Health Sciences Center.

Why This Trial Is Important

The mineral selenium, found naturally in grains, meat, and other common foods, is being studied to see if it can help prevent several types of cancer. Proteins in the body that incorporate selenium have antioxidant properties and help repair damaged cells, which may reduce the risk of cancer. Although studies of the relationship between selenium in foods and cancer risk have been inconclusive, some studies of selenium supplementation have yielded promising results. In particular, the Nutritional Prevention of Cancer Trial ⁴, designed to see if selenium supplements could prevent nonmelanoma skin cancer, found that selenium supplements were associated with reduced risks of colorectal and other cancers.

"That study was a major justification for doing a randomized controlled trial with a colorectal cancer-related endpoint," said Dr. Lance.

In this trial, patients who have a history of colorectal adenoma—noncancerous growths (polyps) found in the colon or rectum that can be precursors to colorectal cancer—will be randomly assigned to receive daily selenium supplements or a placebo for 3 or 5 years. At the end of the supplementation period, patients will have a colonoscopy to check for adenoma recurrence.

Whether patients in the study are treated for 3 or 5 years is at the discretion of the treating physician; some patients at higher risk of adenoma recurrence will undergo colonoscopy 3 years after adenoma removal, while lower risk patients will have their colonoscopy after 5 years.

The investigators plan to follow the patients for 5 years after the end of supplementation. In addition to seeing if patients taking selenium have a lower risk of adenoma recurrence and advanced adenomas (adenomas closer to becoming cancer), the trial will characterize any side effects observed with long-term, high-dose selenium supplementation.

For More Information

See the lists of entry criteria and trial contact information ³ or call the NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). The toll-free call is confidential.

Glossary Terms

A substance that protects cells from the damage caused by free radicals (unstable molecules made by the process of oxidation during normal metabolism). Free radicals may play a part in cancer, heart disease, stroke, and other diseases of aging. Antioxidants include beta-carotene, lycopene, vitamins A, C, and E, and other natural and manufactured substances.

Examination of the inside of the colon using a colonoscope, inserted into the rectum. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

Skin cancer that forms in basal cells or squamous cells but not in melanocytes (pigment-producing cells of the skin).

An inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo.

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.

A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.