Impact of CT-assessed changes in tumor size after neoadjuvant chemotherapy on pathological response and survival of patients with esophageal squamous cell carcinoma

Purpose Neoadjuvant chemotherapy (NAC) followed by surgery is the standard treatment for advanced esophageal squamous cell carcinoma (ESCC) in Japan. Computed tomography (CT) is usually used to assess the therapeutic effect of NAC; however, there are no reliable criteria for predicting pathological response or patient prognosis. Methods We included 84 patients who underwent esophagectomy between January 2009 and December 2018 and retrospectively reviewed their CT scans performed before and after NAC. The reduction rate of the largest tumor area (TA), long diameter (LD), and short diameter (SD) were measured on a transverse CT image. The pathological response and cutoff values were calculated using the receiver operating characteristic curve, and the most suitable ones for determining the effect were examined. Results The areas under the curve for predicting responders to NAC based on the reduction rate of the TA, LD, and SD were 0.755, 0.761, and 0.781, respectively. The optimal cutoff value of the SD reduction rate for predicting responders to NAC was 22%. An SD reduction ≥ 22% was an independent prognostic factor for overall survival in univariate ( p = 0.005, hazard ratio [HR] = 2.755) and multivariate analyses ( p = 0.030 HR 2.690). Furthermore, an SD reduction of ≥ 22% was also an independent prognostic factor for relapse-free survival in the univariate ( p = 0.007, HR = 2.491) and multivariate analyses ( p = 0.007, HR = 0.030). Conclusions The reduction rate of the tumor SD is a simple predictor of pathological response and patient prognosis.