Abstract
Purpose/Objective: Esophagitis are one of the acute treatment related toxicities to definitive radiotherapy for NSCLC. Most current researches about the risk factors for acute esophagitis are based on 3DCRT. The purpose of this study was to estimate the dose-effect relationship between esophagitis and clinical and dosimetric parameters in the patients with local advanced NSCLC receiving IMRT and concomitant chemotherapy (CCT). Materials and Methods: Between 2009 and 2013, 117 patients with stages IIB-IIIB NSCLC enrolled in the multi institution clinical trial NARLAL. All patients were treated with 2 cycles of induction chemotherapy followed by IMRT and CCT (fixed dose of vinorelbine 50 mg three times per week). The maximal esophagitis grade was prospectively scored using the Common Toxicity Criteria 3.0. Clinical and dosimetric variables were analyzed for the correlation with grade >2 esophagitis though multivariable logistic regression. The optimal dose metrics were chosen using Akaike Information Criterion (AIC). All models included one dose position parameter, one dosimetric parameter, gender, and institution. Dose position was defined as the average relative position (zero at start of esophagus and one at the end) irradiated above a certain dose. The dose variable was either maximum dose, mean dose, the physical length of esophagus irradiated above a specific dose (Lx), or the relative volume of esophagus irradiated above a specified dose (Vx). To validate the impact of the fixed dose of vinorelbine, the body surface area was also tested within the models. Data are those collected July 2014 and will be updated. Results: Grade 1 esophagitis was experienced by 50 (43%), grade 2 by 30 (26%), and grade 3 by 10 (8%) patients, respectively. The dose parameter in the two models with lowest AIC was the relative volume irradiated above 40 Gy (V40) (OR=2.39 per additional 10% volume, p