Colonoscopy surveillance after colorectal cancer surgery: meta-analysis

Colonoscopy surveillance is recommended following colorectal cancer (CRC) surgery, yet the evidence supporting the recommendations has major quality issues. This study assessed the independent impact of colonoscopy surveillance within 5 years after CRC surgery.

A systematic review and meta-analysis were conducted. Medline, Scopus, Web of Science, and the Cochrane Central Register of Controlled Trials were searched from inception until 18 June 2026 for randomized clinical trials comparing follow-up protocols including colonoscopy surveillance (intervention) to those without colonoscopy surveillance (control) within 5 years after CRC surgery. Risk of bias was assessed using the RoB 2 tool. Random-effects meta-analyses were conducted to estimate the strength of associations with recurrence detection, reoperation rate, and survival. The number needed to scope (NNS) to detect one recurrence and health economic considerations were estimated. The study protocol has been registered in PROSPERO.

Of 4381 records, five trials with 2337 patients were included. Four trials enrolled patients between 1983 and 1994, predating subsequent advances in CRC treatment. All trials used additional surveillance modalities, leading to a high risk of bias. Follow-up protocols with colonoscopy were not associated with recurrence profile, with risk ratios (RRs) of 0.74 (95% confidence interval (c.i.) 0.32 to 1.69), 1.23 (95% c.i. 0.93 to 1.63), and 0.93 (95% c.i. 0.76 to 1.14) for intraluminal, locoregional, and distant recurrence, respectively. Colonoscopy during follow-up was associated with a higher rate of asymptomatic recurrence (RR 2.38; 95% c.i. 1.53 to 3.69). More curative-intent reoperations were performed in the intervention than control group (RR 1.66; 95% c.i. 1.16 to 2.37), but this was not translated into improved survival (hazard ratio 0.92; 95% c.i. 0.77 to 1.11). The NNS was 159 (95% c.i. 101 to 267), resulting in estimated cost per colonoscopy-detected recurrence of €104 100 (95% c.i. €66 200 to 174 900).

Current evidence from randomized trials does not clearly demonstrate that postoperative colonoscopy surveillance improves survival, although interpretation is limited by the age of the trials and confounding from concurrent surveillance modalities. Contemporary randomized trials are required to better define the independent contribution of colonoscopy within modern multimodal surveillance pathways.