Main Session

Sep 28

PQA 02 - Lung Cancer/Thoracic Malignancies, Patient Reported Outcomes/QoL/Survivorship, Pediatric Cancer

2480 - Cardiac Toxicity Following SBRT for Centrally Located Lung Tumors: Assessing the Impact of Radiation Dose Metrics

04:45pm - 06:00pm PT

Hall F

Screen: 12

POSTER

Presenter(s)

James Shen, MD, PhD - Yale Therapeutic Radiology, New Haven, CT

J. Shen¹, P. Oh², T. J. Hayman², C. A. Knowlton³, D. F. Hicks⁴, J. H. Laird Jr^2,5, and H. S. M. Park⁴; ¹Yale Department of Therapeutic Radiology, New Haven, CT, ²Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, ³Yale University, New Haven, CT, ⁴Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT, ⁵Yale University School of Medicine, New Haven, CT

Purpose/Objective(s): Stereotactic Body Radiotherapy (SBRT) is an established treatment modality for patients with early-stage non-small cell lung cancer (NSCLC) and oligometastatic lung disease, particularly in patients who are not surgical candidates. However, the potential cardiac toxicities associated with SBRT, specifically for centrally located tumors, remains poorly defined. We aimed to evaluate the association between cardiac dose metrics and the incidence of cardiac events following the use of SBRT.

Materials/Methods: We conducted a single-institution retrospective analysis of patients with centrally located lung tumors (<2 cm of the heart) treated with SBRT. Patient records were reviewed to identify whether they developed a post-SBRT cardiac event, including arrythmia, pericarditis, and coronary artery disease (CAD). Cardiac dose metrics were extracted from dose-volume histogram (DVH) data including mean heart dose, maximum heart dose (Dmax), and small volumes doses (D0.01cc, D0.03cc, D1cc). Univariable Cox proportional hazards regression was performed to assess associations between cardiac dose metrics and the incidence of cardiac events. Kaplan-Meier survival analysis was used to estimate overall survival (OS), and the log-rank test compared survival distributions between patients with and without post-SBRT cardiac events.

Results: Among 50 patients included for analysis, the median age at treatment was 74 years (range: 54-89) with a median follow-up of 45 months (range: 4-100). The most common tumor locations were the LLL and RLL (n=12 each), followed by the LUL and RML (n=11 each), with the RUL being the least frequent (n=4). Twenty patients (40%) experienced a post-SBRT event. The most common events were new-onset atrial fibrillation/flutter (n=13), other arrhythmia (n=10), and pericarditis (n=3). Time to first post-SBRT cardiac event was 31.7 months. Univariable regression analysis demonstrated no significant association between cardiac dose metrics and the development of cardiac events. The 2-year OS was 78% and 5-year OS was 28%. There was no significant difference in OS between patients who developed cardiac events and those who did not (46.6 vs. 43.7 months, p = .670).

Conclusion: In this cohort of patients treated with SBRT near the heart, cardiac dose metrics were not associated with an increased risk of post-treatment cardiac events. While new cardiac events occurred frequently after SBRT, post-SBRT cardiac toxicity was not associated with OS. Further research is warranted to determine whether specific cardiac substructures contribute to an increased risk of clinically significant morbidity.