SERRATED POLYPS INCREASE RISK OF COLORECTAL CANCER

NEW YORK (Reuters Health) Nov 25 - Large or proximal serrated polyps are associated with an increased risk of neoplasia and colorectal cancer (CRC), and their presence should trigger more frequent surveillance, according to two studies published online in the November Gastroenterology.

In the first study, researchers in Japan found on multivariate analysis that patients with large serrated polyps (LSPs) were four times more likely to have advanced neoplasia, while their risk of CRC was 3.34-fold greater.

The other study, conducted by researchers from Portland VA Medical Center and Oregon Health and Science University, found that during follow-up colonoscopies of patients who had been initially screened, the 39 who had no neoplasia but did have proximal ND-SP (nondysplastic serrated polyps) were 3.14 times as likely to develop neoplasia compared to those without polyps.

"Based on the best available data, we propose a modification to the current surveillance guidelines that explicitly recognizes the importance of large or proximal serrated polyps," Dr. Jonathan P. Terdiman and Dr. Kenneth R. McQuaid write in an editorial. "Key to our recommendations is recognition that serrated polyps once removed require endoscopic surveillance similar to that recommended in patients with traditional colonic adenomas."

Serrated adenomas were long considered benign, the editorialists note. But despite growing evidence that these lesions may be associated with neoplasia and cancer, they add, the guidelines remain silent on their clinical importance.

To investigate the significance of serrated polyps, Dr. Sakiko Hiraoka of the Okayama University Graduate School of Medicine in Okayama and colleagues looked at 10,199 people who had first-time colonoscopies. Within the cohort, 15.4% of patients had advanced neoplasia, 6.9% had CRC, and 1.4% had large serrated polyps (10 mm or larger).

LSPs were the most important risk factor for CRC, especially proximal disease, with an odds ratio of 4.79. The OR of proximal CRC was 5.36 for proximal LSPs, and 9.00 for protruded LSPs.

In the other study, Dr. Mitchal A. Schreiner and colleagues report on 3,121 asymptomatic patients 50 to 75 years old who had screening colonoscopies, 1,371 of whom were followed for up to 5.5 years. Proximal nondysplastic serrated polyps (ND-SP) were found in 7.9% of patients at initial screening; 17.3% of these patients had advanced neoplasia, compared to 10% of patients without proximal ND-SP. Patients with large ND-SP (10 mm or larger) were 3.37 times as likely to have synchronous advanced neoplasia.

Based on the findings, Dr. Schreiner and his colleagues suggest patients with proximal or large ND-SP undergo a surveillance schedule similar to that used for patients with one to two tubular adenomas smaller than 10 mm.

And in patients with ND-SP along with advanced neoplasia, they add, "strict adherence to guidelines recommending 3-year surveillance should be encouraged."

Gastroenterology. 2011;139:1497-1502, 1503-1510. Abstract, Abstract