Cytoreductive surgery for colorectal peritoneal metastasis in the era modern systemic therapies: a systematic review and meta-analysis of survival outcomes.

Introduction: The value of surgical cytoreduction over modern systemic therapy in patients with colorectal peritoneal metastasis is debated. The present systematic review and meta-analysis aimed to determine the magnitude of the benefit of cytoreduction for peritoneal metastasis over varying intensities of palliative therapies.

Methods: The databases searched were PubMed, Cochrane Library, Scopus, CINHAL (EBSCO) and Google Scholar. The risk of bias was assessed using the RoB2 tool for randomized studies and the Newcastle-Ottawa scale for non-randomised studies. The certainty of the evidence was assessed using the GRADE Pro tool. The analysis used the log hazard ratio as the outcome measure for survival data with the random-effects model. Sensitivity analyses and meta-regressions were performed to establish the robustness of the results.

Results: The quantitative meta-analysis included two randomised and nine non-randomized studies with 3316 patients. The pooled hazard ratio for overall survival was 0.447 (95% CI: 0.387 to 0.595; p-< 0.001) favouring cytoreduction without statistical heterogeneity (I² = 0%) or publication bias. There was moderate certainty of evidence, that was downgraded due to clinical heterogeneity among studies and the risk of bias from non-randomized studies. Sensitivity analyses and meta-regression confirmed that the pooled hazard ratio remained unchanged irrespective of the systemic therapies used or the risk of bias of individual studies.

Conclusions: Curative intent treatment of colorectal peritoneal metastasis by adding cytoreductive surgery over systemic chemotherapy alone, increased the OS by a large magnitude with moderate certainty of evidence, irrespective of the systemic therapy used.