Sessile Serrated Lesions Associated With Higher Risk for Colorectal Cancer

Endoscopic surveillance is recommended in patients with sessile serrated lesions (SSLs), large SSLs, SSLs with dysplasia, or SSLs with synchronous adenomas.

Patients with sessile serrated lesions (SSLs) alone or with synchronous adenomas have an increased risk for colorectal cancer (CRC) compared with individuals without polyps, according to a study in Gut.

Researchers sought to stratify the risk for CRC in patients with a history of SSLs, hyperplastic polyps (HPs), or unspecified serrated polyps (SPs) after expert pathologic rereview and reclassification of all historically diagnosed SPs.

The nested case-control study was conducted among members of a community-based, integrated health care delivery system in California. The participants were aged 50 to 85 years, with a first colonoscopy documented between 2006 and 2016 and with at least 1 year of enrollment before the first documented colonoscopy.

Tissue slides of SPs from the first colonoscopy were retrieved from the pathology archive and were reviewed by 2 expert pathologists. The SPs were reclassified into a subtype: traditional serrated adenoma (TSA), SSL, unspecified SP, or HP according to current World Health Organization diagnostic criteria. The outcome of interest was CRC diagnosis.

Patients with large SSLs or SSLs with dysplasia have the highest risk and should benefit from close surveillance.

The analysis included 317,178 individuals, of whom 695 (women, 52.4%) had CRC more than 1 year after the first colonoscopy. The patients were matched with 3475 control individuals (women, 52.4%). Of the cohort, 785 patients (162 cases and 623 control individuals) had at least 1 SP identified on their first colonoscopy, and 3385 patients (533 cases and 2852 controls) did not have an SP on their first colonoscopy.

Patients who had an SSL were more likely to have CRC (adjusted odds ratio [aOR], 2.9; 95% CI, 1.8-4.8), as were those with both SSL and synchronous adenoma (aOR, 4.4; 95% CI, 2.7-7.2). Patients with SSL without dysplasia had an aOR of 3.3 (95% CI, 2.1-5.2), and dysplasia was associated with an aOR of 10.3 (95% CI, 2.1-50.3).

HP alone was not associated with an increased risk for CRC (aOR, 0.8; 95% CI, 0.5-1.3). Men had an aOR for SSL alone of 1.7 (95% CI, 0.8-3.8) compared with 4.4 (95% CI, 2.3-8.2) for women.

Proximal and distal unspecified SP were associated with aORs of 5.8 (95% CI, 2.2-15.2) and 0.9 (95% CI, 0.4-2.1), respectively. The aORs for proximal large SSL and proximal small SSL were 12.8 (95% CI, 3.5-46.9) and 1.9 (95% CI, 0.8-4.7), respectively.

Study limitations include a limited overall number of cases, which precluded meaningful analysis of the CRC risk in some subgroups, including patients with TSAs, or further stratifying the risk. In addition, the researchers were unable to assess CRC risk after the surveillance colonoscopy, and it is possible that SPs were underdetected in the early years of the study, potentially leading to underestimation of their risk or that these polyps were resected less effectively than would have occurred in current practice.

“Our study provides further evidence supporting an increased risk [for] CRC associated with SSLs in a large, diverse, community-based setting,” the study authors concluded. “Patients with large SSLs or SSLs with dysplasia have the highest risk and should benefit from close surveillance. Patients with small proximal SSLs also have an increased risk and may benefit from surveillance.”


Li D, Doherty AR, Raju M, et al. Risk stratification for colorectal cancer in individuals with subtypes of serrated polyps. Gut. 2022;71:2022-2029. doi:10.1136/gutjnl-2021-324301