Study: Some Colon Polyps May Be Precursors of Colon Cancer

Some colon polyps previously considered to be harmless may be precursors of colon cancer, according to researchers at the University of South Wales and St. Vincent's Hospital in Sydney, Australia.

Sporadic malignancies in the right side of the colon that show a genetic mutation (DNA microsatellite instability) may come from specific types of benign abnormal tissue.

"Recognition of this possibility has important implications for research on the key genetic changes underpinning tumor progression in this group of cancers," said the researchers in their study published in the Journal of the National Cancer Institute.

Researchers report that their findings give statistical and biologic evidence that serrated polyps, including hyperplastic polyps and serrated adenomas, are likely to be the precursor lesions of sporadic colorectal cancers with microsatellite instability (MSI).

Patients with cancer showing MSI were four times more likely to have at least one serrated polyp than patients whose cancers showed microsatellite stability (MSS). They were also nearly four times more likely to have at least one hyperplastic polyp, the researchers said.

Several of the polyps from patients with MSI cancers had another gene mutation linked with cancer, but none of the polyps from cancer patients with MSS had that mutation, said the researchers.

The researchers concluded, "Accurate determination of the risk of developing carcinomas from right-sided serrated polyps and the screening implications of the detection of such lesions will only be determined in large prospective studies that recognize the unique biologic significance and malignant potential of these lesions."

Other Sources: Journal of the National Cancer Institute