Severe late esophagus toxicity in NSCLC patients treated with IMRT and concurrent chemotherapy

Background and purpose: We reported the incidence of severe late esophagus toxicity (LET) in locally advanced NSCLC patients treated with intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy. Acute esophagus toxicity (AET) and the dose to the esophagus were analyzed for their associations with severe LET. Material and methods: Two hundred and thirty-one patients treated from 2008 to 2011 with hypofractionated IMRT (66 Gy/24 fx) and concurrent daily low dose cisplatin were included. The association between AET and severe LET (grade ⩾3 RTOG/EORTC) was tested through Cox-proportional-hazards model. Equivalent uniform dose (EUD) to the esophagus and the volume percentage receiving more than x Gy (Vx) were applied by Lyman–Kutcher–Burman (LKB) model. Results: A total of 171 patients were eligible for this study. Severe LET was observed in 6% patients. Both the maximum grade and the recovery rate of AET were significantly associated with severe LET. In the EUDn-LKB model, the fitted values and 95% confidence intervals (CIs) were TD50 = 76.1 Gy (73.2–78.6), m = 0.03 (0.02–0.06) and n = 0.03 (0–0.08). In the Vx-LKB model, the fitted values and 95% CIs were Tx50 = 23.5% (16.4–46.6), m = 0.44 (0.32–0.60) and x = 76.7 Gy (74.7–77.5). Conclusions: Severe AET, EUD (n = 0.03) and V76.7 to the esophagus were significantly associated with severe LET. An independent validation study is required