Optimal combination of heart and lung dose parameters in radiotherapy for locally advanced non-small cell lung...

This study aimed to identify the optimal combination of heart and lung dose parameters associated with overall survival (OS) in patients with locally advanced non-small cell lung carcinoma (LA-NSCLC) receiving radiotherapy. Data from 278 patients treated definitively for LA-NSCLC at three institutions between 1 April 2013 and 31 October 2021 were retrospectively analyzed. Lung and heart dose parameters were categorized into high- or low-dose groups based on predefined thresholds for subsequent analysis. Univariable analysis of OS was conducted for all dose group combinations. The combination with the lowest P-value was identified as the most promising and included in the multivariable analysis along with other clinical factors. The combinations of mean heart dose (MHD)/lung V40 (LV40) ('Vxx' denotes the percentage of organ volume receiving ≥xx Gy) and heart V5 (HV5)/LV40 yielded the lowest P-values (P = 0.021). The thresholds for these dose parameters were MHD ≤24.4 Gy, HV5 ≤63% and LV40 ≤7.7%, respectively. Multivariable analysis incorporating clinical factors identified age ≥65 years (HR: 2.06, P = 0.002), performance status ≥1 (Hazard ratio [HR]: 1.68, P = 0.024), chemoradiotherapy (HR: 0.28, P < 0.001), current smoking history (HR: 2.21, P < 0.001), gross tumor volume (HR: 1.43, P = 0.007) and the MHD/LV40 combination (HR: 2.35, P = 0.003) as independent prognostic factors. While exploratory, this study highlights the clinical significance of the MHD/LV40 combination as a prognostic factor; integrating these parameters radiotherapy for LA-NSCLC may improve patient outcomes.