Efficacy and safety of the “watch-and-wait” approach for rectal cancer with clinical complete response after neoadjuvant chemoradiotherapy: a meta-analysis

Background Watch-and-Wait (WW) approach is positioned at the cutting edge of non-invasive approach for rectal cancer patients who achieve clinical complete response (cCR) after neoadjuvant chemoradiotherapy (nCRT). This meta-analysis aimed to compare the clinical, oncologic, and survival outcomes of WW versus radical surgery (RS) and to evaluate the efficacy, safety, and possible superiority of WW. Methods A systematic search for studies comparing WW with RS was conducted on MEDLINE, Ovid, Embase, Cochrane Library, and Web of Science databases. After screening for inclusion, data extraction, and quality assessment, statistical analysis was performed using Stata/SE14.0 software. Permanent colostomy (PC), local recurrence (LR), distant metastasis (DM), cancer-related death (CRD), 2-, 3-, and 5-year disease-free survival (DFS), and overall survival (OS) were analyzed using fixed effects or random-effects models depending on the heterogeneity. Results Fourteen studies with moderate-high quality involving 1254 patients were included. Of these, 513 patients were managed with WW and 741 patients were subjected to RS. Compared to RS group, WW group had higher rate of LR (odds ratio OR = 11.09, 95% confidence interval CI = 5.30–23.20, P = 0.000), 2-year OS, and 3-year OS and had lower rate of PC ( OR = 0.12, 95% CI = 0.05–0.29, P = 0.000). There were no significant between-group differences with respect to DM, CRD, 2-, 3-, and 5-year DFS ( OR = 0.92, 95% CI = 0.81–1.03, P = 0.153), or 5-year OS ( OR = 1.01, 95% CI = 0.28–3.63, P = 0.988). Conclusion The WW is a promising treatment approach and is a relatively safe alternative to RS for managing patients with rectal cancer who achieve cCR after nCRT. However, this modality requires rigorous screening criteria and standardized follow-up. Large-scale, multicenter prospective randomized controlled trials are warranted to further verify the outcomes of WW approach.