Impact of pretreatment clinical factors and DVH parameters on radiation pneumonitis and survival after intensity-modulated radiotherapy for lung cancer.

Abstract

e20571 Background: The aim of this study was to investigate the relationship between clinical factors and dose-volume histogram parameters regarding Overall Survival (OS) and Radiation-Pneumonitis-Free Survival (RPFS) in lung cancer patients. Methods: We retrospectively reviewed clinical data of lung cancer patients from 2018 to 2020. Demographic, clinical, and treatment-related data were collected for all patients. OS was defined as the duration from pathological diagnosis to death or last follow-up. RPFS was defined as the duration from the start of radiation therapy to occurrence of grade≥3 Radiation-Pneumonitis, or final follow-up. RPFS and OS rates were estimated with the Kaplan-Meier method and compared using the log-rank test. The Cox regression model was used to estimate the hazard ratio (HR) and the corresponding 95% confidence interval (CI) for univariate and multivariate analysis. Results: A-hundred patients were included in this study. The median follow-up period after completion of radiotherapy was 42.9months (range: 2.0–152.1). In multivariate study, low serum sodium after RT, V5ipsi≥51%, V20ipsi≥28%, V30ipsi≥22% and MLDipsi≥15.99 Gy were independent predictive factors for poor OS, respectively ( p ＜0.05). MLD≥10.20 Gy suggested a poorer RPFS ( p ＜0.1) in this cohort. Conclusions: The independent significant risk factors of radiation pneumonitis were V20, V5 and MLD. In addition, the V20 and V5 of the ipsilateral lung should be more strictly limited to less than 28% and 51% when determining radiotherapy especially in this era of immunotherapy. Some blood indexes of low nutritional status were very important to determine the occurrence of high-risk radiation pneumonitis.