Fig. 2

Findings prior to salvage surgery. a–d Upper gastrointestinal endoscopy 6 years after carbon-ion radiotherapy. An elevated lesion at the previously treated area (27–29 cm from the incisors) was detected by a white light endoscopy and b Lugol staining. In addition, a type 0-IIa lesion located 20–22 cm from the incisors had freshly appeared. c White light endoscopy. d Lugol staining. e Ultrasound endoscopic finding. The tumor located 27–29 cm from the incisors was thought to have infiltrated the submucosal layer. f ¹⁸F-deoxyglucose (FDG) positron emission tomography revealing slight FDG uptake in the middle esophagus (white arrowhead)