Efficacy and safety of neoadjuvant immunotherapy in surgically resectable esophageal cancer: A systematic review and meta-analysis

Background: Neoadjuvant immunotherapy for patients with locally advanced esophageal cancer (EC) has developed rapidly in recent years. The efficacy and safety outcomes may change the recommended neoadjuvant therapeutic regimens for patients with EC. Methods: Systematic screening for articles focusing on the efficacy and safety of neoadjuvant immunotherapy in locally advanced and surgically resectable EC was performed using PubMed, Embase, Web of Science and international tumor congresses. Meta-analysis of non-comparative binary outcomes was carried out to combine the main results. The pooled results were compared with the traditional neoadjuvant chemotherapy (nCT) and chemoradiotherapy (nCRT) using direct comparative analysis. The results were expressed as the risk ratio (RR). Results: A total of 20 articles with 621 patients were included in the present study. The pooled pathological complete response and major pathological response rates were 33.8% (95% CI: 29.6%-37.9%) and 53.5% (95% CI: 47.9%-59%), respectively, in the neoadjuvant immunotherapy combined with chemotherapy (nICT) group and 39.8% (95% CI: 27%-53.9%) and 88.8% (95% CI: 64.8%-97.2%) in the neoadjuvant immunotherapy combined with chemoradiotherapy (nICRT) group, respectively. In addition, the pooled grade 3-4 treatmentrelated adverse events (TRAEs) rate was 19.4% (95% CI: 11.5%-31.5%) in the nICT group. The results of direct comparison showed that compared with nCRT and nICRT, nICT could improve safety while achieving comparable efficacy. The results of subgroup analysis, sensitivity analysis and publication bias evaluation indicated that the above findings were stable and reliable. Conclusion: The current meta-analysis revealed that neoadjuvant immunotherapy in patients with locally advanced EC was safe and effective and nICT could be used as the recommended neoadjuvant therapeutic option for patients with EC. However, additional studies are urgently needed to reveal the long-term outcomes of neoadjuvant immunotherapy.