Abstract: Objective To explore the influencing factors of radiation-induced lung injury (RILI) in esophageal cancer treated with intensity modulated radiation therapy (IMRT). Methods Clinical data of 233 patients with esophageal cancer treated with IMRT in Tumor Hospital affiliated to Xinjiang Medical University from January 2014 to December 2016 were analyzed retrospectively. All of the patients were divided into 2 groups according to whether acute radiation lung injury occurred: with RILI and without RILI. The influencing factors of radiation-induced lung injury were analyzed. Clinical data included age, sex, T staging, lymph node metastasis, pathological type, tumor location, tumor length, chemotherapy mode, KPS score, basic lung disease, diabetes and smoking history. Physical parameters of radiotherapy included double lung V5, V10, V15, V20 and V30, mean lung dose (MLD), gross tumor volume (GTV), two lung volume, GTV volume and two lung volume ratio, field number of irradiated and prescription dose. The risk factors of radiation-induced lung injury were screened by Logistic regression analysis. Results In all groups, there were 63 (27%) patients with RILI, and 25 (10.7%) patients with grade ≥2 RILI. Univariate analysis showed that the positive lymph nodes, GTV volume, GTV volume and two lung volume ratio, MLD, and double lung V5, V10, V15, V20, V30 and prescription dose were significantly different between the two groups. Multivariate analysis showed that V5 ≥63.15% (OR=1.022, 95%CI: 1.003-1.041) and V30 ≥5.35% (OR= 2.693, 95%CI: 1.159-6.010) were risk factors for RILI (P＜0.05). Conclusion The full account of the clinical characteristics and the physical indexes such as V5 and V30 should be considered to minimize the risk of RILI, when evaluating the treatment plan of intensity modulated radiotherapy for esophageal cancer.

Key words:  esophageal neoplasms, radiotherapy, intensity-modulated, radiation pneumonitis, radiation-induced lung injury