Risk analysis of grade ≥ 2 radiation pneumonitis based on radiotherapy timeline in stage III/IV non-small cell lung cancer: a retrospective study

Background: Radiotherapy is an important treatment for patients with stage III/IV NSCLC, and due to its high incidence of radiation pneumonitis , it is essential to identify high-risk people as early as possible. The present work investigates the value of the application of different phase data throughout the radiotherapy process in analyzing risk of grade ≥2 radiation pneumonitis in stage III/IV NSCLC. Furthermore, the phase data fusion was gradually performed with the radiotherapy timeline to develop a risk assessment model. Methods: : This study retrospectively collected data from 91 stage III/IV NSCLC cases. Patient data were collected according to the radiotherapy timeline for four phases: clinical characteristics, radiomics features, radiation dosimetry parameters, and hematological indexes during treatment. Risk assessment models for single-phase and stepwise fusion phases were established according to logistic regression. In addition, a nomogram of the final fusion phase model and risk classification system was generated. ROC, decision curve, and calibration curve analysis were conducted to internally validate the nomogram to analyze its discrimination. Results: : Smoking status, PTV and lung radiomics feature, lung and esophageal dosimetry parameters, and platelets at the third week of radiotherapy were independent risk factors for the four single-phase models. The ROC result analysis of the risk assessment models created by stepwise phase fusion were: (AUC: 0.67,95ci: 0.52–0.81), (AUC: 0.82,95ci: 0.70–0.94), (AUC: 0.90,95ci: 0.80–1.00), and (AUC:0.90,95ci: 0.80–1.00), respectively. The nomogram based on the final fusion phase model was validated using calibration curve analysis and decision curve analysis, demonstrating good consistency and clinical utility. The nomogram-based risk classification system could correctly classify cases into three diverse risk groups: low-(3.6%; score, 0–135), intermediate-(30.7%, 135–160) and high-risk group (80.0%, > 160). Conclusions: : In our study, the risk assessment model makes it easy for physicians to assess the risk of grade ≥ 2 radiation pneumonia at various phases in the radiotherapy process, and the risk classification system and nomogram identify the patient’s risk level after completion of radiation therapy.