Corrigendum: Prognostic significance of FDG PET/CT in esophageal squamous cell carcinoma in the era of the 8th AJCC/UICC staging system - Hyunjong Lee; Kyung Soo Lee; Yang Won Min; Hong Kwan Kim; Jae Ill Zo; Young Mog Shim; Joon Young Choi (Frontiers in Oncology)