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

Abstract

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 (66Gy/24fx) 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.

Keywords: Acute esophagus toxicity; Concurrent chemoradiation; IMRT; Late esophagus toxicity; NTCP; Non small cell lung cancer (NSCLC).