Construction of a nomogram prediction model of grade ≥2 radiation pneumonitis in patients with unresectable locally advanced esophageal carcinoma after combined radiation/immunotherapy

Objective To explore the risk factors for grade ≥2 radiation pneumonitis in patients with unresectable locally advanced esophageal carcinoma after combined radiation/immunotherapy, and to construct a nomogram prediction model. Methods A total of 110 patients with unresectable locally advanced esophageal carcinoma who received the combined radiotherapy/immunotherapy in the Affiliated Hospital of Xuzhou Medical University from January 2020 to January 2023 were selected, and their clinical data were collected for retrospective analysis. The observation index was the occurrence of radiation pneumonitis within six months after the completion of chest radiotherapy. Univariate and multivariate logistic regression analyses were used to determine the independent risk factors for the occurrence of grade ≥2 radiation pneumonitis in patients with unresectable locally advanced esophageal carcinoma after treatment and a prediction model was constructed. Results Among 110 esophageal carcinoma patients included in this study, 33 (30.0%) patients developed grade≥2 radiation pneumonitis. Multivariate logistic regression analysis showed that age, smoking history, planned target volume (PTV), and V₂₅ (percentage of volume of the lungs receiving a dose of 25 Gy) were the independent predictors of the occurrence of grade≥2 radiation pneumonitis after treatment in patients with unresectable locally advanced esophageal carcinoma. The receiver operating characteristic (ROC) curve showed that the sensitivity and specificity of the established nomogram in the current study were 0.758 and 0.818, with an area under curve (AUC) value of 0.851 (95%CI: 0.776-0.926), indicating that the nomogram had good discriminatory ability. The calibration curve showed high consistency between the actual incidence of grade≥2 radiation pneumonitis and the predicted incidence of grade≥2 radiation pneumonitis from the nomogram. Decision curve analysis further confirmed that the model showed good clinical benefit. Conclusions The study provides a nomogram model containing age, history of smoking, PTV and V₂₅, which can be used for individualized prediction of grade ≥ 2 radiation pneumonitis in patients with esophageal carcinoma after combined radiation/immunotherapy.