According to a University of Pittsburgh-led study published in the December issue of Gastroenterology, medium-sized polyps found in the colon with flexible sigmoidoscopy and subsequently evaluated by full colonoscopy are associated with a significant number of advanced adenomas (high-risk polyps) and cancers.
These findings raise questions about taking a "wait and watch" approach to medium-sized polyps and delaying referral to colonoscopy, a strategy which could become more popular with newer screening tests that are observational and do not remove polyps, such as virtual colonoscopy.
The study included 10,850 men and women enrolled in the Prostate, Lung, Colorectal and Ovarian Cancer (PLCO) Screening Trial, a randomized, community-based study evaluating the effectiveness of cancer screening tests on site-specific mortality at 10 centers throughout the United States. The participants in the study had an abnormal flexible sigmoidoscopy with at least one detectable polyp and subsequently underwent a diagnostic colonoscopy within one year.
"An emerging issue in colorectal cancer screening is the management of medium-sized polyps, since many new technologies under development can only observe the lining of the colon, and do not offer the ability to remove polyps," said Robert Schoen, M.D., M.P.H, lead author of the study and professor of medicine and epidemiology, University of Pittsburgh School of Medicine. "With these new methods, colonoscopy and polyp removal are required as second procedures, but because of issues of expense and risk, determining a specific threshold for subsequent procedures becomes an important issue. One area of uncertainty concerns medium-sized polyps. In our study, individuals with medium-sized polyps 0.6 - 0.9 cm were found to have a significant yield of advanced adenomas and even cancer, making an observational strategy in this setting potentially risky."