Reducing the risk of grade 3 or greater radiation pneumonitis after radical radiotherapy to the lung.

e20008 Background: Radiation pneumonitis (RP) is the most common adverse response in patients with lung cancer receiving thoracic radiotherapy. Higher grade RP is more likely to lead to mortality and poor quality of life, which could be abated by rigorous treatment standards formulated with individualized clinical characteristics. In this study, we aimed to identify the best clinical prognostic model for evaluating patients with lung cancer after radical radiotherapy. Methods: We collected information of RP patients in recent years and established the new consensus on the diagnosis and treatment of radiation-related pneumonitis. In a nutshell, clinical data of patients treated with radical radiotherapy were collected from August 2020 to August 2022, and part of patients from August 2021 to August 2022 was been intervented by treatment methods. The interventions included limited irradiation of the planning target volume (PTV), individualized lung dose limitation, and standardized steroid therapy. Clinical characteristics including baseline and treatment data were obtained from 693 patients, including 623 patients in the training cohort and 70 patients in the test cohort. Three models were built using different screening methods, including multivariate logistics regression (MLR), backward stepwise regression (BSR), and random forest regression (RFR), to evaluate their prognostic power. Overoptimism in the training cohorts was evaluated by four validation methods including hold-out, 10-fold, leave-one-out, and bootstrap methods, and extra data were used to evaluate the predictive performance of the model. Model calibration, Decision curve analysis (DCA), and evaluation of the nomograms for the three models were completed. Results: The incidence of RP was significantly decreased after the interventions compared to before (68.80% vs. 59.56%, P 86.9%, and total lung volume exceeding 5 Gy (V5) > 35.2% for the radiological parameter had the best discriminative ability with an area under the curve of 0.963 (95% CI: 0.938–0.989) in the training chort . The calibration curve showed good agreement between the predicted and actual values, and the DCA showed a positive net benefit for the final model based on the nomogram. Conclusions: The implementation of standardized interventions for the prevention and treatment of RP accompanied with standardized use of steroids resulted in a significant decrease in the incidence of grade 3 or higher RP. Early intervention and methods for reducing the complications of high-dose steroids will be explored in future work.