Individuals with serrated polyps (SPs) are at an increased risk for colorectal cancer (CRC) 3 years after SP removal, according study results published in Gastroenterology.

Researchers retrospectively recruited patients who had received a colonoscopy at Kaiser Permanente Northern California (N=233,393) between 2006 and 2016. Patients were grouped into cohorts based on the size and location of SPs found during colonoscopy procedures.

A total of 445 patients developed CRC over the 10-year span of the study. The hazard ratios (HR) for the association of CRC diagnosed more than 1 year after colonoscopy were determined for each subgroup of patients. The hazard ratio was 4.7 (95% CI, 4.0-5.6) for patients with no polyps; 5.9 (95% CI, 3.6-9.5) for patients with distal SPs; 14.8 (95% CI, 9.0-24.3) for patients with proximal small SPs; and 30.2 (95% CI, 13.2-68.4) for patients with proximal large SPs.


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The risk for CRC increased 3 years after preliminary colonoscopy, with a HR of 0.8 for small proximal SPs (95% CI, 0.3-2.7) at less than 3 years and 2.6 (95% CI, 1.7-3.9) 3 years and after. The HR for large proximal SPs was 2.1 (95% CI, 0.3-15.4) at less than 3 years and 8.0 (95% CI, 3.6-16.1) 3 years and after.

The risk for CRC increased when SPs were concurrent with synchronous adenomas. Proximal SPs and synchronous adenomas had a HR of 4.0 (95% CI, 3.0-5.5) and distal SPs with synchronous adenomas had an HR of 2.4 (95% CI, 1.7-3.4).

A limitation of the study is that researchers did not distinguish SPs into sessile serrated lesions or hyperplastic polyps. Patient data was collected before the concept of distinguishing between these 2 subtypes was developed, making retrospective categorization impossible.

The study authors concluded, that in this large cohort study, risk for CRC was increased in individuals with proximal SPs, especially large SPs, at 3 years or more after initial colonoscopy. These results were consistent with current guidelines of CRC surveillance.

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Reference

Li D, Liu L, Fevrier H B, et al. Increased risk of colorectal cancer in individuals with a history of serrated polyps. [available online April 8, 2020] Gastroenterology doi:10.1053/j.gastro.2020.04.004