FDG-PET might not contribute to improving survival in patients with locally advanced inoperable esophageal cancer Abstract Background In Japan, positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) has been covered by the national health insurance for esophageal cancer since 2006. FDG-PET is commonly performed in advanced esophageal cancer. The aim of this study was to determine the effect of FDG-PET on survival in patients with locally advanced inoperable esophageal cancer. Methods We retrospectively reviewed all patients with cT4 and without M1 esophageal cancer on CT in our institution between 2000 and 2014, and data for 78 patients who meet the eligibility criteria described below were used for analysis in this study. The eligibility criteria included (1) cT4 esophageal cancer without distant metastases or M1 lymph node metastasis (UICC 2002), (2) histologically proven squamous cell carcinoma, (3) 20–79 years of age, (4) having undergone at least 1 cycle of concomitant chemotherapy, (5) having been irradiated with 50 Gy or more, and (6) no other active malignant tumor during treatment. Results Two patients were excluded because abdominal lymph node metastases or neck lymph node metastases were detected by FDG-PET. In 78 eligible patients, FDG-PET was not performed before treatment in 41 of the 78 patients and was performed in the other patients. The median observation period was 68 months. The 3-year and 5-year overall survival rates in 78 patients were 36.9% and 30.8%, respectively. There was no significant difference in overall survival or progression-free survival between patients in whom FDG-PET was performed and those in whom FDG-PET was not performed (12.0 months vs. 11.0 months, p = 0.920 and 6.0 months vs. 6.0 months, p = 0.844, respectively). Conclusions Compared with only CT, additional information from FDG-PET is not associated with improving survival in patients with locally advanced esophageal cancer. Our results suggest that FDG-PET might not have much meaning for survival in locally advanced esophageal cancer.