Predictive factors for radiation-induced lung injury in locally advanced non-small cell lung cancer after intensity-modulated radiotherapy

Abstract

Objective To investigate the incidence of radiation-induced lung injury (RILI) in patients with locally advanced non-small cell lung cancer (LA-NSCLC) after involved-field intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy, and to figure out the predictive factors for RILI. Methods Two hundred and fifty-six patients with stage Ⅲ NSCLC who were treated without surgery in our hospital from January 2007 to December 2011 were enrolled as subjects. All patients received involved-field IMRT with a median dose of 60 Gy (50-70 Gy) in 30 fractions. In all patients, 109 patients (42.6%) received concurrent chemotherapy. The National Cancer Institute Common Terminology Criteria for Adverse Events Version 3.0 was used to evaluate the RILI grade. The incidence of grade ≥2 RILI (symptomatic RILI, SRILI) within 6 months after radiotherapy served as the end point. The predictive factors for RILI were analyzed using logistic regression model. Results In all patients, 215(84%) were male, and 41(16%) were female. The mean age at diagnosis was 59.2 years. Forty-three (16.7%) patients had grade ≥2 RILI. The mean duration between the incidence of RILI and the beginning of radiotherapy was 64 days (20-169 days). Univariate analysis showed that smoking, peripheral or central tumor location, mean lung dose (MLD) for both lungs, and V5-V20 for both lungs were suspected to be associated with the development of SRILI (P=0.108, 0.106, 0.030, 0.049). Multivariate analysis showed the MLD and V5-V20 for both lungs were independent predictive factors for SRILI P=(0.048). Conclusions For patients with LA-NSCLC treated with involved-field IMRT, the MLD and the volume of low-dose region in dose volume histogram for both lungs are significantly correlated with the incidence of SRILI. Key words: Cacinoma, non-small cell lung/intensity modulated radiotherapy; Cacinoma, non-small cell lung/chemotherapy; Symptomatic radiation induced lung injury