Efficacy of neoadjuvant immunotherapy in advanced colorectal cancer: a meta-analysis of cross-sectional studies.

BACKGROUND: Although neoadjuvant immunotherapy is being widely studied, there is no consensus on its efficacy in microsatellite-stable (MSS) or mismatch repair proficient (pMMR) colorectal cancer (CRC). This meta-analysis aimed to evaluate studies on neoadjuvant immunotherapy for advanced CRC to assess its efficacy and provide new clinical guidelines. METHODS: We searched literature databases to identify studies that assessed the efficacy of neoadjuvant immunotherapy in advanced CRC. The outcomes evaluated were pathological complete response (pCR), major pathological response (MPR), R0 resection, and anal preservation rates. Heterogeneity among the included studies was assessed by sensitivity analysis, and publication bias was evaluated using Begg and Egger tests. RESULTS: Eleven articles were included in the analysis. The pCR, MPR, R0 resection, and anal preservation rates reported in these studies were 39 and 49, 97, and 76%, respectively. The MSI-H and MSS groups had pooled pCR rates of 70 and 24%, respectively. The pCR rates for the induction, consolidation, and concurrent immuno-chemoradiotherapy (CRT) subgroups were 43, 33, and 27%, respectively, and those for the single and double immunotherapy subgroups were 34 and 40%, respectively. CONCLUSION: Neoadjuvant immunotherapy combined with CRT is effective in treating MSI-H/dMMR advanced CRC. It could also be a new first-line therapeutic option for MSS/pMMR advanced CRC.