Phase III Randomised Study of Selenium in Patients with Adenomatous Colorectal Polyps
Dr. M. Peter Lance, of the Arizona Cancer Center at the University of Arizona Health Sciences Center, is running a trial to compare daily selenium supplements with a placebo in patients with non cancerous growths in the rectum and colon.
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 the relationship between selenium in the diet and cancer risk is unclear, some studies of selenium supplementation have yielded promising results. In particular, the Nutritional Prevention of Cancer Trial, designed to see if selenium supplements could prevent nonmelanoma skin cancer, found that the supplements were linked with reduced risks of lung, prostate, and colorectal cancer.
"That study was a major justification for doing a randomised 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 either 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 need a surveillance colonoscopy at 3 years after adenoma removal, while lower risk patients will have a surveillance 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 characterise any side effects observed with long-term, high-dose selenium supplementation.
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