Sessile Serrated Polyps with Synchronous Conventional Adenomas Increase Risk of Future Advanced Neoplasia

Surveillance colonoscopy guidelines following adenomas or sessile serrated adenomas/polyps (SSPs) are based on pathology features known to be associated with risk of future colorectal cancer. A synchronous conventional adenoma may increase the malignant potential of SSP, but current guidelines do not address this combination of pathologies.

The aim was to assess the risk of advanced neoplasia after SSP with or without synchronous adenoma compared to that following a conventional adenoma.

An audit was conducted on colonoscopies performed between 2000 and 2014 as part of a surveillance program. Index colonoscopy findings were classified as: low-risk SSP and high-risk SSP (size ≥ 10 mm or with cytological dysplasia) with and without synchronous adenoma; high-risk adenoma and low-risk adenoma. Risk of advanced neoplasia was determined at subsequent surveillance colonoscopies.

In total, 2157 patients had adenoma or SSP found at index colonoscopy-low-risk adenoma (40%), high-risk adenoma (54%) and SSP (4%). Synchronous adenomas were seen with 47% of SSP. The median follow-up was 50.3 months (interquartile range 28.1-79.3). Compared to an index finding of low-risk adenoma, index findings of high-risk adenoma, as well as SSP with synchronous adenoma, were independent predictors of future advanced neoplasia (high-risk adenoma: hazard ratio (HR) = 2.04 (95% CI 1.70-2.45); high-risk SSP + adenoma HR = 3.20 (95% CI 1.31-7.82); low-risk SSP + adenoma: HR = 2.20 (95% CI 1.03-4.68)).

Synchronous adenoma increases the risk of advanced neoplasia for SSP equivalent to that seen following high-risk adenoma. Guidelines for surveillance should take into account concurrent pathologies with SSP.