Serrated polyps up long-term risk of colorectal cancer

Having proximal serrated polyps (SPs), particularly large ones, is a risk factor for the long-term development of colorectal cancer (CRC), a recent study has found.

Researchers conducted a retrospective analysis of 233,393 individuals who had undergone colonoscopy. Participants were categorized according to the size (large, small, or unknown) and location (proximal or distal) of SP. The outcome of interest was the development of CRC >1 year after the first colonoscopy.

Over a median follow-up of 3.6 years, 445 patients developed CRC more than a year after colonoscopy. The 5-year cumulative incidence rate for CRC varied according to the presence of polyps, and their size and location. Those with no polyps, for instance, had a cumulative incidence rate of 1.2 per 1,000 persons.

In those with proximal small, proximal large, and distal SPs, the resulting cumulative incidence rates were 2.5, 6.2, and 1.7 per 1,000 persons, respectively.

Cox proportional hazards analysis confirmed these findings. Having SP alone increased the long-term risk of incident CRC (adjusted hazard ratio [HR], 1.7, 95 percent confidence interval [CI], 1.3–2.2). This effect was amplified by the co-presence of adenoma (adjusted HR, 3.1, 95 percent CI, 2.4–4.0).

Further stratification showed that small proximal (adjusted HR, 2.6, 95 percent CI, 1.7–3.9) and large proximal (adjusted HR, 8.0, 95 percent CI, 3.9–16.1) SPs significantly increased the risk of incident CRC ≥3 years after the initial colonoscopy.