['To explore the values of sequential (18)F-FDG PET/CT scanning in patients with non-surgical esophageal squamous cell carcinoma (ESCC) who received concurrent chemoradiotherapy (CCRT).', 'Twenty-eight patients with pathologically confirmed stage I-IV ESCC and who received definitive CCRT were prospectively enrolled into this trial. The (18)F-FDG PET/CT scans were performed four times. The maximum standardized uptake values (SUVmax) of each scanning were named as SUVmaxpet1, SUVmaxpet2, SUVmaxpet3, and SUVmaxpet4, respectively. The tumor volume with SUV greater than 40% of SUVmax was named as metabolic tumor volume (MTV). Follow-up investigation of patients was performed to record progression-free survival (PFS), relapse-free survival (RFS), and overall survival time (OS).', 'The average value of MTV before treatment is 19.3 ml. The average value of SUVmax at four time points was 13.0 ± 7.4, 6.4 ± 3.2, 4.7 ± 1.9, and 3.4 ±1.8, respectively. Median follow-up time was 18.5 months (range 5-40). There was statistically significant difference in ΔR14 ((SUVmaxpet1- SUVmaxpet4) / SUVmaxpet1). Multivariate Cox regression survival analysis indicated that the MTV was an independent prognostic factor for PFS and RFS (HR = 1.13 and 1.14, respectively) before treatment.'] Does application of sequential ( 18 ) F-FDG PET/CT scan for concurrent chemoradiotherapy of non-surgical squamous cell esophageal carcinoma?