Acute Radiation-induced Esophagitis as a Novel and Early Predictor for Radiation-Induced Pneumonitis: A Real-World Study

Abstract

Radiation-induced pneumonitis (RP) is a non-negligible and life-threatening complication in patients undergoing thoracic radiation. We have observed that many patients with severe RP (SRP, grade≥2) were accompanied with severe acute radiation-induced esophagitis (SARE, grade≥2) in clinic. The aim of this study was to ascertain the application value of SARE to SRP and establish a novel and visible nomogram model for it. Patients with thoracic cancer who were treated with thoracic radiation from Jan.2018 to Jan.2019 in Shandong Cancer Hospital and Institute were enrolled prospectively. All patients were followed up during and after radiotherapy (RT) to observe the appearance of esophagitis and pneumonitis. Variables were analyzed by univariate and multivariate analysis using the logistic regression model, and a nomogram model was established to predict SRP by "R” version 3.6.0. A total of 123 patients were enrolled (64 esophageal cancer, 57 lung cancer and 2 mediastinal cancer) in this study prospectively. With a median follow-up of 3.3 months (range 1–14.2 months), RP grades of 0, 1, 2, 3, 4 and 5 occurred in 29, 57, 31, 0, 3 and 3 patients, respectively. SRP appeared in 37 patients (30.1%). In univariate analysis, SARE was shown to be a significant predictive factor for SRP (P < 0.001). The incidence of SRP in different grades of ARE were as follows: Grade 0-1:6.52%; Grade 2: 36.92%; Grade 3: 80.00%; Grade 4: 100%. Besides that, the dosimetric factors considered total lung mean dose, total lung V5, V20; ipsilateral lung mean dose, ipsilateral lung V5, and mean esophagus dose to be correlated with SRP (all P < 0.005) in univariate analysis. The incidence of SRP was significantly higher in patients whose symptoms of RP appeared early. SARE (HR 34.408, P = 0.001), mean esophagus dose and ipsilateral mean lung dose were still significant in multivariate analysis, and they were included to build a predictive nomogram model for SRP. SARE was the first intuitive index that can reflect the radiation sensitivity of normal tissue visually. It could be a significant predictor to SRP for patients receiving thoracic radiation, which can be earlier and easier than previously reported laboratory or clinical indicators. And the nomogram model could assist in doctor’s decision and guide to make personalized radiation dose prescription.