Nationwide Validation Study of the Prognostic Significance of Stratification Using Pathological Stage and Response to Neoadjuvant Chemotherapy for Esophageal Squamous Cell Carcinoma

Objective:This study aimed to validate the prognostic significance of stratification using pathological stage and response to neoadjuvant chemotherapy with a nationwide database from an authorized institute by the Japan Esophageal Society. Background:We proposed the combined criteria using pStage and pathological response. Conducting a validation study using an expanded cohort in the clinical setting would be valuable since it was developed using retrospective data collection. Methods:Patients with esophageal squamous cell carcinoma who underwent subtotal esophagectomy at 85 authorized institutes were retrospectively reviewed for esophageal cancer between 2010 and 2015. The prognostic value of the pathological response was evaluated within the same pStage. Moreover, risk stratification was developed to predict cancer-specific survival (CSS). Results:The pathological response showed significant stratification of CSS in 3761 patients included in this analysis. We classified the patients into 7 groups as survival was significantly different between responders and nonresponders under the stratification with pStage, excluding pStage I comprising pStage 0-I/II responder/II nonresponder/III responder/III nonresponder/IV responder/IV nonresponder with the 5-year CSS of 83.7%/75.8%/68.9%/59.8%/44.4%/40.7%/23.1%, respectively. Furthermore, the area under the curve was significantly higher under the new classification than in the pStage alone (P<0.001). Conclusions:The prognostic value of classification using pStage and the pathological response was successfully validated using real-world data in Japan. This result would guide appropriate treatment for patients with esophageal squamous cell carcinoma who received neoadjuvant chemotherapy followed by esophagectomy.