Presenter(s)
I. Ratosa1,2, K. Sketa1, A. Tomazin1, U. Elbl2,3, M. Sojar2, D. Brojan2, and J. But Hadzic1,2; 1Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia, 2Division of Radiotherapy, Institute of Oncology Ljubljana, Ljubljana, Slovenia, 3Department of Oncology, University Medical Centre Maribor, Maribor, Slovenia
Purpose/Objective(s):
In lung cancer radiotherapy, a higher mean heart dose (Heart Dmean) independently increases the risk of major adverse cardiac events (MACE), including heart failure, acute coronary syndromes, arrhythmias, and pericardial disease. We hypothesized that radiation dose to the heart and its substructures correlates with MACE and all-cause mortality (ACM) in patients with lung cancer treated with radiotherapy.Materials/Methods: All patients treated for locally advanced, inoperable lung cancer at a single institution from 2018 to 2022 with radical or high-dose palliative radiotherapy were included in this study. Medical charts were reviewed for treatment characteristics and medical history. Cardiac substructures were retrospectively contoured on all CT simulation scans using an AI-based auto-contouring tool. Dose-volume histograms (DVH) were subsequently extracted from the treatment planning system for analysis.
Results:
The median age of the cohort was 68 years (range, 36–88), and 60.1% of the 460 included patients were male. Pre-treatment coronary heart disease (CHD) was present in 71.5% of patients (n=329), while 28.5% (n=131) had no documented cardiac comorbidities (CHD-negative). After a median follow-up of 28.5 months (range, 1.6–95.6), the 2-year cumulative incidence of new major adverse cardiac events (MACE) was 15.7%. Patients with pre-existing CHD had approximately double the risk of developing new post-treatment cardiac events compared to CHD-negative patients (18.2% vs. 9.2%; p=0.016). However, pre-treatment CHD status did not significantly impact median overall survival (OS: 28.4 vs. 29.7 months; p=0.596). The median Heart Dmean was 9.1 Gy (range, 5.6–34.8). Higher Heart Dmean was significantly associated with increased risk of MACE in CHD-negative patients (p=0.016), but not in patients with pre-existing CHD (p=0.244). When stratified by Heart Dmean (=20 Gy vs. <20 Gy), higher doses (in the whole cohort) were associated with worse all-cause mortality (ACM), reflected in inferior median OS (23.5 vs. 31.1 months; p=0.020). This association was pronounced in CHD-negative patients (OS: 20.6 vs. 37.5 months; p=0.028), whereas no significant difference was observed among CHD-positive patients (OS: 26.8 vs. 27.5 months; p=0.190). Additionally, among CHD-negative patients, left ventricle dose-volume parameters were significantly associated with ACM, including left ventricle V10 Gy (=10 cm³ vs. <10 cm³; OS 23.6 vs 42.5 months; p=0.026) and left ventricle V15 Gy (=1% vs. <1%; OS: 25.9 vs 44.1 months; p=0.045).Conclusion:
Particularly in patients without a history of heart disease, Heart Dmean = 20 Gy and Ventricle L V15 =1 % and/or V10 Gy = 10 cm3 were all strong predictor of all-cause mortality. These findings suggest that these cardiac dose parameters should be considered as potential dose-guidance in future radiotherapy protocols for lung cancer, with the aim of improving long-term survival outcomes.