Effect of consolidation chemotherapy following definitive chemoradiotherapy in patients with esophageal squamous cell cancer

Definitive chemoradiotherapy (dCRT) is a treatment option for patients with localized esophageal squamous cell carcinoma (ESCC). We investigated consolidation chemotherapy (CCT) in patients with ESCC who attained clinical complete response after dCRT. Between January 2009 and December 2012, medical records of ESCC patients treated with dCRT were retrospectively reviewed, and those who attained CCR were identified. Progression-free survival and overall survival rates were estimated by the Kaplan-Meier method. The Cox regression model was used to determine prognostic factors. Of the 522 patients treated with dCRT, 209 patients achieved CCR, with 67 receiving consolidation chemotherapy (the CCT group) and 142 receiving dCRT alone (the control group). CCT did not prolong progression-free survival (33.0 vs 18.0 months, P = 0.07, HR = 0.70, 95% CI, 0.48-1.04); however, CCT improved the median overall survival (53.4 vs 27.0 months, P = 0.04, HR = 0.67, 95% CI, 0.44-0.99) compared with dCRT alone. CCT remained a favorable prognostic factor for overall survival in a multivariate analysis (HR = 0.59, P = 0.02); however, a propensity score analysis failed to show an additional overall survival benefit with CCT. In the present analysis, CCT did not improve progression-free survival but may have extended overall survival in ESCC patients who achieved complete clinical response after dCRT.