Fear of missing bowel cancer may be exposing patients to unnecessary risks

Professor Geir Hoff and colleagues in Norway, argue that we need more evidence about the malignant potential of benign lesions to be sure that the risks of removing them do not outweigh the benefits of screening.

Bowel cancer screening has increased the detection of benign polyps (fleshy growths on the lining of the colon or rectum). The most common polyps found during screening are adenomas and guidelines recommend that they are removed.

However, data show that less than 5% of adenomas develop into colorectal cancer, suggesting that 95% of procedures may be exposing patients to unnecessary risks.

This concern about malignancy has now been extended to sessile serrated polyps which, the authors warn, are "less understood than adenomas and are more risky to remove."

Yet current consensus guidelines advise doctors to remove sessile serrated polyps measuring more than 5mm in diameter. Patients with sessile serrated polyps also undergo repeat colonoscopy every 1-5 years (a procedure involving a long tube with a camera on the end that is inserted via the rectum).

"The risk is that by adopting consensus guidelines the medical profession misses out on the opportunity to learn about the natural course of sessile serrated polyps and try different management options," write Professor Hoff and his team.

With more polyps being detected as a result of screening, "we need to be able to quantify the gains and harms and share this information with screening participants," they add. "It is not enough simply to share a belief that we are doing good, partly motivated by fear of not doing enough."

They acknowledge that guidelines are needed, but say they "should not be allowed to impair essential research to determine the malignant potential and best management of sessile polyps."

The change in guidelines towards an aggressive intervention strategy for sessile serrated polyps "may tilt the balance against screening if the improvements in mortality and incidence of colorectal cancer cannot be shown to outweigh the harms of intervention," they conclude.