(HealthDay News) — For individuals who have had at least one adenoma removed at colonoscopy, the risk of developing colorectal cancer is greatly reduced up to five years later, according to a study published online June 23 in the Journal of Clinical Oncology.

Hermann Brenner, M.D., M.P.H., from the German Cancer Research Center in Heidelberg, and colleagues examined the risk of colorectal cancer based on time since adenoma removal at colonoscopy in 2,582 patients with a history of at least one adenoma removal and 1,798 matched controls who had never undergone large-bowel endoscopy.

The researchers found that the risk of colorectal cancer was reduced in patients who had undergone polypectomy compared to those without previous endoscopy, with adjusted odds ratios of 0.2 for polypectomy less than three years earlier, 0.4 for polypectomy three to five years earlier, and 0.9 for polypectomy six to 10 years earlier. The reduction in risk within five years of adenoma removal was consistently found in both genders and all age groups examined and regardless of the presence of high-risk polyps and polypectomy in the right colon. In addition, the risk was particularly reduced in those with left-sided colorectal cancer.

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“Our study provides further support for suggestions that surveillance colonoscopy may be postponed to five to 10 years after detection and removal of low-risk adenomas and furthermore suggests possible prolongation of surveillance intervals to five years, even in the case of high-risk adenomas,” Brenner and colleagues conclude.

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