Colonoscopy used to identify and remove flat colon lesions

A study released this week from researchers at the Veterans Affairs Palo Alto Healthcare System in California shows that non-polypoid colorectal neoplasms or flat colon lesions, are more common in Americans than previously thought and may have a greater association with cancer compared to polypoid neoplasms or the more commonly diagnosed colorectal polyp. The study appears in the March 5 issue of the Journal of the American Medical Association. Researchers identified these flat lesions through colonoscopy.

“This study is very significant, as these flat lesions are more difficult to detect than the typical polyp during colorectal cancer screening,” said Grace H. Elta, MD, FASGE, president of the American Society for Gastrointestinal Endoscopy (ASGE). “Researchers identified these lesions in their study through colonoscopy, which has the ability to detect lesions of all sizes and is the only procedure that allows for the removal of lesions and polyps. Studies have shown that other imaging methods are ineffective at identifying even small polyps and miss flat lesions entirely. This study highlights the importance of quality colonoscopy screening. ASGE, as the standard-setting society for endoscopy, has issued quality indicators for colorectal cancer screening that define measures for improving quality in colonoscopy.”

Flat lesions are challenging to detect because subtle findings through examination can be difficult to distinguish from the normal mucosa. As compared with the surrounding normal mucosa, the flat lesions appear to be slightly elevated, completely flat or slightly depressed.

The study examined data from a group of 1,819 patients, almost all men with an average age of 64, from July 2003 to June 2004 undergoing elective colonoscopy to estimate the prevalence of non-polypoid colorectal neoplasms (NP-CRNs), or flat lesions, and to characterize their association with colorectal cancer. Patients were divided into three groups; screening, surveillance and a group of patients with symptoms for colorectal cancer. Flat lesions were found in 170 people, approximately 10 percent. The surveillance group had the highest incidence with more than 15 percent who had flat lesions. Approximately six percent of the screening and symptoms groups had flat lesions. Researchers found that the flat growths were five times more likely to be cancerous than polyps.

“Experts in gastrointestinal endoscopy will need to be more vigilant than ever in encouraging their patients to take their bowel prep as directed before the colonoscopy. Proper bowel prep is important so that the physician can clearly see the colon. This study also highlights the importance of not withdrawing too soon during the procedure, allowing the physician enough time to thoroughly examine the colon. According to ASGE quality indicators, withdrawal time should be six minutes or more. ASGE will continue to provide training and education to physicians to ensure that patients are receiving the highest quality of care possible,” said Elta.