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Are Hyperplastic Polyps Precursors of Colorectal Cancer?

Adenomatous polyps, but not hyperplastic polyps, traditionally are considered to be precursors of colorectal cancer. But new research suggests that hyperplastic polyps also may be associated with some colorectal cancers. These cancers are particularly likely to have microsatellite instability (MSI) -- an abnormality in non-protein-coding portions of DNA -- and tend to occur in the right side of the colon.

Australian investigators examined resection specimens from 355 patients who underwent curative resections of colorectal cancer. They identified 29 cases of sporadic colorectal cancer that showed MSI on analysis of tumor DNA and compared these cases with 29 control cases of colorectal cancer that did not show MSI. The 2 groups of patients had similar numbers of conventional adenomas in their resection specimens. In contrast, specimens from patients with MSI harbored a significantly higher number of hyperplastic polyps: The MSI group included 12 patients with 114 hyperplastic polyps, whereas the control group included 4 patients with 4 hyperplastic polyps. MSI also was found in several hyperplastic polyps from patients whose cancers exhibited MSI.

Comment: An editorialist acknowledges the need for additional research, but he concludes that "the truism that hyperplastic polyps lack malignant potential has bitten the dust as a result of the findings." Currently, patients in whom hyperplastic polyps are detected by colonoscopy or sigmoidoscopy are not considered to be at higher risk for colorectal cancer than are patients with no polyps. That belief might change if these findings are corroborated.

— AS Brett

Published in Journal Watch General Medicine September 14, 2001

Citation(s):

Hawkins NJ and Ward RL. Sporadic colorectal cancers with microsatellite instability and their possible origin in hyperplastic polyps and serrated adenomas. J Natl Cancer Inst 2001 Sep 5 93 1307-1313.

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Hamilton SR. Origin of colorectal cancers in hyperplastic polyps and serrated adenomas: Another truism bites the dust. J Natl Cancer Inst 2001 Sep 5 93 1282-1283.

• Original article (Subscription may be required)
• Medline abstract (Free)