Study of The Predictors for Radiation Pneumonitis in Patient With Non-Small Cell Lung Cancer Received Radiotherapy After Pneumonectomy

Abstract Background: To identify the valuable predictors of grade≥2 radiation pneumonitis (RP) in patient treated with radiotherapy after pneumonectomy for non-small cell lung cancer (NSCLC); and to construct a nomogram predicting the incidence of grade≥2 RP in such patients.Methods: We reviewed 74 patients with NSCLC received radiotherapy after pneumonectomy from 2008 to 2018. The endpoint was grade≥2 RP. Univariate and multivariate regression analysis were conducted to evaluate significant factors of grade ≥2 RP. Receiver operating characteristic (ROC) curve was used to establish optimal cutoff values and the nomogram was built to make the predictive model visualized. Descriptive analysis was performed on 5 patients with grade 3 RP. Results: A total of 25(33.8%) patients developed grade≥2 RP and 5(6.8%) patients were grade 3 RP. V5, V10, V20, V30, MLD, PTV, and PTV/TLV were associated with the occurrence of grade≥2 RP in univariate analysis, while none of the clinical factors was significant; V5(OR,1.195;95%CI,1.082-1.319; P<0.001) and V20(OR,1.412;95%CI,1.161-1.717; P=0.001) were the independent significant predictors by multivariate analysis and were included in the nomogram. The ROC analysis for the cutoff values for predicting grade≥2 RP were V5>22%(AUC=0.816, sensitivity:0.712, specificity:0.837) and V20>8%(AUC=0.822, sensitivity:0.681, specificity:0.828). Additionally, grade≥3 RP did not occur when V5<30%, V20<13% and MLD<751.2cGy, respectively.Conclusions: Our study showed that V5 and V20 were independent predictors for grade≥2 RP in NSCLC patients receiving radiotherapy after pneumonectomy. Grade 3 RP did not occur whenV5<30%, V20<13% and MLD<751.2cGy, respectively. In addition, patient underwent right pneumonectomy may have a lower tolerance to radiation compared to left pneumonectomy.