Increased risk of metachronous large serrated polyps in individuals with 5 to 9 mm proximal hyperplastic polyps: data from the New Hampshire Colonoscopy Registry.

BACKGROUND AND AIMS: Because data on metachronous risk for patients with index proximal 5 to 9 mm hyperplastic polyps (HPs) are limited, the clinical significance of these polyps is unclear. Conversely, published data suggest that sessile serrated polyps (SSPs), traditional serrated adenomas (TSAs) and large (>1 cm) hyperplastic polyps (HPs) are high-risk lesions requiring close surveillance. We used data from the New Hampshire Colonoscopy Registry (NHCR) to examine the risk of metachronous large serrated polyps (SPs) and advanced adenomas in patients with 5 to 9 mm proximal HPs. METHODS: We included adults with at least 1 polyp resected at index colonoscopy and a surveillance examination 12 months or more after index. Outcomes were risk for metachronous large (>1 cm) SPs and advanced adenomas (AA) (>1 cm, villous elements, HGD or CRC). Individuals were hierarchically stratified by the most significant index SP. The risks for adults with proximal 5 to 9 mm HPs at index examination were compared with individuals with index findings of: large (>1 cm) HPs, or any SSPs or TSA; nonsignificant HPs ( 3 adenomas) (no SPs) and low-risk adenomas (no SPs). We present absolute and adjusted risks of metachronous polyps from a regression model which included age, sex, BMI, smoking, previous polyp history, family history of CRC, year of diagnosis, endoscopist serrated polyp detection rates and months to surveillance examination. RESULTS: A total of 8560 NHCR participants were included (44.8% women, average age 59.0 years, SD 9.1). Similar to those with large HPs or any SSPs/TSAs at index examination (OR, 7.63; 95% CI, 4.78-12.20), individuals with proximal 5 to 9 mm HPs had an elevated risk for metachronous large SPs (OR, 4.77; 95% CI, 2.54-8.94) as compared with adults with low-risk conventional adenomas. CONCLUSIONS: NHCR data suggest that similar to adults with large HPs or any SSPs or TSAs at index examination, individuals with index 5 to 9 mm HPs proximal to the sigmoid are at an increased risk for metachronous large SPs. These novel data suggest that close surveillance intervals may be appropriate for patients with 5 to 9 mm proximal HPs.