Nationwide survey of neuroendocrine carcinoma of the esophagus: a multicenter study conducted among institutions accredited by the Japan Esophageal Society.

Background Esophageal neuroendocrine carcinoma (ENEC) is an extremely rare type of tumor characterized by a high malignant potential, rapid growth, and poor prognosis. Because the standard therapy for ENEC has been poorly defined, we herein aimed to attain a clear view of the current state of treatment for ENEC by performing a large-scale, multicenter study. Methods We conducted a questionnaire-based, retrospective clinical review of 142 patients with ENEC treated at 37 hospitals accredited by the Japan Esophageal Society from January 2010 to December 2015. Results The most frequent main treatment performed was an operation, followed by chemoradiotherapy, chemotherapy, and endoscopic submucosal dissection. Among the 67 patients who underwent surgery, 28 (19.7%) were not accurately diagnosed with NEC or a combined NEC tumor by pretreatment biopsy. The 5-year overall survival rate of all patients was 33.2%. Among patients with Stages III and IV disease, the prognosis was significantly better in patients who underwent chemoradiotherapy than in patients who underwent other treatments. Among patients with Stages I and II disease, however, there was no difference in survival rates between those who underwent surgery and chemoradiotherapy. Conclusions This nationwide survey is a valuable report of the current status of treatment of ENEC in a limited number of cases experienced at each participating institution. The survival benefit obtained from surgery was considered to be limited, especially for Stages III and IV ENEC. Accurate pretreatment histological diagnosis is essential to determine the most appropriate treatment strategy for patients with ENEC.