Serrated polyps in the colorectum: clinical significance and future directions

Serrated polyps are believed to play an important role in the development of colorectal cancer (CRC). They share molecular characteristics and proximal colonic location with postcolonoscopy colorectal cancer (PCCRC), indicating that they may give rise to a disproportionately high proportion of PCCRC. In this narrative literature review, we aimed to synthesise the current understanding of serrated polyps and their role in the development of CRC. Our review focuses on the prevalence of serrated lesions in various populations, risk of progression to advanced colorectal neoplasia and cancer, and the effect of serrated polyp detection on PCCRC rates. Serrated polyp detection is noted to be variable between studies based on the type of serrated polyps studied and the patient population in question. In addition, low-risk sessile serrated lesions (SSLs) do not seem to have a higher risk for progression to advanced neoplasia than conventional adenomas, while more advanced lesions (10 mm or larger, those with dysplasia and traditional serrated adenomas) do seem to have a higher malignant potential, particularly in combination with traditional adenomas. Finally, several studies demonstrate a decrease in PCCRC rates among endoscopists with higher serrated polyp detection metrics. We identified a need for standardising the definition of clinically significant serrated polyps for future monitoring and benchmarking of serrated polyp detection metrics, further research to determine the surveillance interval for patients with concomitant adenomas and serrated polyps, and widespread education and training for endoscopists and pathologists to improve detection, diagnosis and management of serrated lesions.