Colorectal Cancer Risk Tied More to Colonoscopy Factors Than Polyp Features

August 22, 2012

NEW YORK (Reuters Health) Aug 20 - When colonoscopy reveals a polyp, the risk of cancer may depend more on colonoscopy-related factors than on the polyp itself, German researchers say.

Dr. Hermann Brenner from the German Cancer Research Center, Heidelberg and colleagues studied 155 case subjects and 260 controls with a physician-validated colonoscopy with detection of polyps in the past 10 years.

Lack of complete removal of all polyps and lack of surveillance colonoscopy within five years were strongly independently associated with later development of colorectal cancer.

As for polyp characteristics, only the occurrence of multiple (i.e., at least three) polyps was independently associated with a moderately increased risk for cancer.

The presence of at least one colonoscopy-related characteristic (incompleteness, poor bowel preparation, incomplete removal of all polyps, or no surveillance colonoscopy within five years) accounted for 41.1% of the cancer risk, compared with only 21.7% for the presence of at least one of the following polyp characteristics: 1 cm or larger, villous components or high-grade dysplasia, at least three polyps, or at least one proximal polyp.

In fact, the researchers note, colonoscopy-related factors accounted for a larger share of cancer risk than polyp characteristics for all defined population subgroups and for all cancer stage and site subgroups.

The association between lack of surveillance colonoscopy within five years and cancer risk was especially strong in the youngest age group.

"The 2 most important factors identified (lack of removal of all polyps and lack of surveillance colonoscopy within five years) point to important approaches for prevention by enhanced adherence to follow-up procedures and surveillance, particularly among high-risk patients in whom not all polyps could be completely removed," the investigators conclude.

"Further research should aim for more comprehensive identification of reasons for colorectal cancer occurring after colonoscopic polyp detection and for the most effective ways to prevent them," the researchers say.


Ann Intern Med 2012;157:225-232.


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