Serrated Polyps and the Risk of Metachronous Colorectal Advanced Neoplasia: A Systematic Review and Meta-Analysis

Surveillance recommendations for serrated polyps (SPs) are based on insufficient evidence. We aimed to evaluate the risk of metachronous advanced colorectal neoplasia (ACRN) associated with SPs.We searched all relevant studies published through August 2020 that examined the risk of SPs for developing metachronous lesions. We performed meta-analyses of the risk of metachronous ACRN or colorectal cancer (CRC) between patients with SPs (or sessile serrated lesions [SSLs]) alone and those with conventional adenomas alone, and between patients with synchronous SPs (or SSLs) and conventional adenomas and those with conventional adenomas alone.Eleven studies with 1,079,315 patients were included in the meta-analysis. No significant differences in the risks of metachronous ACRN and CRC were found between the SPs alone and conventional adenomas alone groups (odds ratio [OR] [95% confidence interval [CI]]: ACRN, 0.70 [0.27-1.82]; CRC, 0.74 [0.47-1.14]). The risks were similar between SSLs alone and conventional adenomas alone (OR [95% CI]: ACRN, 0.91 [0.23-3.63]; CRC, 1.11 [0.42-2.97]). Significant heterogeneity was identified in these comparisons. Synchronous SPs (or SSLs) and high-risk adenomas (HRAs) had a higher risk of metachronous ACRN than HRAs alone (OR [95% CI]: SPs+HRAs, 1.64 [1.21-2.24]; SSLs+HRAs, 3.10 [1.92-4.99]); however, there was no difference in the risk between synchronous SPs (or SSLs) and low-risk adenomas and low-risk adenomas alone.The results of this meta-analysis support the current guidelines, which recommend similar surveillance intervals for SSLs and conventional adenomas. Patients with synchronous SPs (or SSLs) and HRAs appear to be at an increased risk of metachronous ACRN, and further studies are needed to determine whether they require more intensive surveillance.