Background: We aimed to evaluate dosimetric, clinical parameters, and survival factors contributing to the risk of radiation pneumonia in lung cancer patients treated with volumetric-modulated arch therapy (VMAT) and helical tomotherapy (HT). Materials and Methods: Retrospective analysis of 79 lung cancer patients treated between January 2018-2020, with 54 eligible patients. Radiotherapy using HT and VMAT at a total dose of 60Gy. Lung volumes receiving >5, 10, 20 Gy, mean lung dose, and organ doses were recorded. The associations among clinical factors, dose-volume parameters, grade >3 RP, and survival outcomes (OS, LRFS, DMFS) were analyzed. Results: Median follow-up: 18.9 months (range 10.1-34.4). Median OS: 17 months, with 1- and 2-year OS rates of 71.8% and 45.2%, respectively. Univariate analysis showed significant associations with OS for mean lung dose, lung V5Gy, V10 Gy, V20Gy, mean esophagus dose, esophagus V20Gy, V60Gy, heart V40Gy, and grade >3 RP (all p<0.05). For LRFS, significant factors included PTV% 95 coverage >59Gy, PTV volume <55cm3, esophagus V20Gy, and grade>3 RP (all p<0.05). In multivariate analysis, lung V5 Gy, V10 Gy, mean esophagus dose, esophagus V20 Gy, V60 Gy, heart V40 Gy, and grade >3 RP remained significant for OS, while PTV volume was significant for LRFS. Lung volumes of V5, V10, and V20 strongly associated with grade>3 RP. Conclusion: In this study we found that low-dose lung volumes and doses to organs at risk (esophagus, heart) are not only significant for radiation pneumonitis (RP) but also play a crucial role in overall survival in arch treatments. |
