PITTSBURGHA study published in the December issue of Gastroenterology has shown that 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 and cancers.
These findings raise questions about taking a "wait and watch" approach to medium-sized polyps and delaying referral to colonoscopy, said Robert E. Schoen, MD, MPH, lead author of the study and professor of medicine and epidemiology, University of Pittsburgh School of Medicine. He noted that wait and watch could become more popular with wider use of newer screening tests that visualize polyps but do not remove them, such as CT (virtual) colonoscopy and less-invasive colonoscopies on the horizon such as the Aer-O-Scope (a miniaturized, self-propelling, self-navigating, disposable colonoscopic camera).
There is general agreement that colonoscopy is needed when a polyp 1.0 cm in size or larger is found, he said, but there is much greater uncertainty about the role of colonoscopy when the polyps are less than 1.0 cm."Because of issues of expense and risk, determining a specific threshold for subsequent procedures after these observational screening tests becomes an important issue," he said.
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 US centers. The participants had an abnormal flexible sigmoidoscopy with at least one detectable polyp and subsequently underwent a diagnostic colonoscopy within 1 year.
Polyps 0.5 to 0.9 cm were found in 2,183 men and 1,426 women through flexible sigmoidoscopy. When the men and women underwent diagnostic colonoscopy, 14.5% of the women and 15.9% of the men were diagnosed with advanced adenomas, and 0.6% of the women and 0.7% of the men were diagnosed with cancer. In some cases, the medium-sized polyps were considered large after removal, he said, and some small polyps were found to have important, adverse pathologic characteristics.
"The implication is that where we draw the line when assessing polyp size and referral to colonoscopy has to be carefully considered," Dr. Schoen said. "These results offer a cautionary note to waiting and watching."