HOUSTON - Supplementation with a selenium-based antioxidant compound decreased the risk of developing new polyps of the large bowel -- called colorectal metachronous adenomas -- in people who previously had colorectal polyps removed.
"Our study is the first intervention trial specifically designed to evaluate the efficacy of the selenium-based antioxidant compound on the risk of developing metachronous adenomas," said Luigina Bonelli, M.D., head of the unit of secondary prevention and screening at the National Institute for Cancer Research, in Genoa, Italy.
Bonelli presented these findings at the American Association for Cancer Research Frontiers in Cancer Prevention Research Conference, held in Houston, Dec. 6-9, 2009.
Adenomatous polyps (or adenoma) are benign lesions of the large bowel that, in time, could progress to cancer. Even though only a small proportion of adenomas will develop into cancer, almost 70 percent to 80 percent of colorectal cancer stems from an adenoma.
Adenomas are common in people aged 60 years or older; one in four people will have at least one adenoma.
Participants in this study were aged 25 to 75 years and had already had one or more colorectal adenomas removed, but did not have any other diagnosis of colorectal diseases, cancer or life-threatening illnesses and did not use vitamins or calcium supplementations. The researchers randomized 411 participants to the placebo group or to receive an antioxidant compound -- specifically selenomethionnine 200 μg, zinc 30 mg, vitamin A 6,000 IU, vitamin C 180 mg and vitamin E 30 mg.
"Our results indicated that individuals who consumed antioxidants had a 40 percent reduction in the incidence of metachronous adenomas of the large bowel," Bonelli said. "It is noteworthy that the benefit observed after the conclusion of the trial persisted through 13 years of follow up."
The researchers are currently conducting a study to evaluate the role of genetic alterations as predictors of metachronous adenomas in participants received the antioxidant compound compared with those in a placebo group.
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The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, the AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes 30,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and nearly 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants, research fellowship and career development awards. The AACR Annual Meeting attracts more than 16,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes six major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.