Incidence and Mortality of Post-Polypectomy Colorectal Cancer in Patients with Low-Risk Adenomas: A Systematic Review and Meta-Analysis of Observational Studies.

Introduction: The long-term risks of post-polypectomy colorectal cancer (CRC) incidence and mortality among patients with low-risk adenomas (LRAs) are unclear. This study aimed to perform a systematic review and meta-analysis of the risk of CRC incidence and mortality following LRAs removal.

Methods: We searched the PubMed, Embase, and Cochrane library for studies that reported the risk of metachronous CRC incidence and mortality after colonoscopy. The primary outcome was the risk of CRC incidence and mortality in patients with LRAs. Random-effects models were used to calculate the pooled risk ratio (RR) with a 95% confidence interval (CI).

Results: Thirteen observational studies with 1,750,305 patients (45.4% male; follow-up: 4.5-16.5 years) were included. A meta-analysis of seven studies showed a higher CRC incidence in patients with LRAs than those without adenomas (per 10,000 person-years: 5.2 vs. 3.9; RR 1.25 [95% CI 1.05-1.49], I2 = 0%). However, the CRC-related death rate was not significantly different between the two groups (RR 1.13 [95% CI 0.75-1.69], I2 = 0%). When compared with the general population, the meta-analysis showed a significantly lower risk of CRC incidence in patients with LRAs (RR 0.59 [95% CI 0.45-0.77], I2 = 0%), and another three studies, which could not be pooled, showed a reduction in the risk of CRC-related death in the LRAs group.

Conclusions: Patients with LRAs have a small but higher risk of post-polypectomy CRC incidence than patients without adenomas. The marginally higher absolute incidence seemed insufficient for more intensive surveillance colonoscopy, but the significant difference suggested different follow-up strategies between patients with LRAs and those without adenomas.