Retrospective analysis of neoadjuvant chemotherapy followed by surgery versus definitive chemoradiotherapy with proton beam for locally advanced esophageal squamous cell carcinoma.

Background This is the first study to compare the long-term outcomes between neoadjuvant chemotherapy + surgery and definitive chemoradiotherapy with proton beam therapy for locally advanced esophageal squamous cell carcinoma. Methods We reviewed patients with clinical stage IB-III esophageal squamous cell carcinoma (UICC 7th edition) who underwent neoadjuvant chemotherapy + surgery or definitive chemoradiotherapy with proton beam therapy (2009-2017). Overall survival, progression-free survival, and recurrence or regrowth rates were compared between the two treatment groups. Subgroup analyses of overall survival according to baseline characteristics were also performed. Results Forty-three patients received neoadjuvant chemotherapy + surgery (median follow-up 47.4 months) and 60 received definitive chemoradiotherapy with proton beam therapy (median follow-up 51.5 months). Baseline characteristics were similar between the groups except for sex, tumor location, and cT classification. The neoadjuvant chemotherapy + surgery and definitive chemoradiotherapy with proton beam therapy groups had similar 3-year overall survival rates (73.1% and 61.7%, respectively, hazard ratio: 0.88, 95% confidence interval 0.49-1.58, p = 0.66), 3-year progression-free survival rates (46.5% and 45%, respectively, hazard ratio: 1.03, 95% confidence interval 0.62-1.70, p = 0.92), and recurrence or regrowth rates (53.5% vs. 50.0%, p = 0.84). In the subgroup analysis, favorable survival was observed after definitive chemoradiotherapy with proton beam therapy for cT1-2 disease (hazard ratio 2.58, 95% confidence interval 0.84-7.99) and after neoadjuvant chemotherapy + surgery for cT3 or higher disease (hazard ratio 0.32, 95% confidence interval 0.15-0.67, p-for-interaction = 0.002). Conclusions Long-term outcomes were comparable between the treatments. The choice of the treatment according to cT classification might affect survival.