272 - A Feasibility and Toxicity Analysis of Single Fraction Stereotactic Body Radiation Therapy for Post-Operative Non-Small Cell Lung Cancer
Presenter(s)
M. K. Farrugia1, N. K. Malik2, S. Fung-Kee-Fung3, M. Hennon1, S. Yendamuri1, E. Dexter1, C. Nwogu1, K. P. Seastedt1, T. Demmy1, and A. K. Singh2; 1Roswell Park Comprehensive Cancer Center, Buffalo, NY, 2Department of Radiation Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY, 3University at Buffalo, State University of New York, Buffalo, NY
Purpose/Objective(s): Post-operatively radiotherapy (PORT) can reduce the risk of mediastinal failure following resection in patients with N2 non-small cell lung cancer (NSCLC) however at the expense of increased cardiopulmonary toxicity. Alternative radiotherapeutic regimens may convey improved oncologic outcomes with a more favorable toxicity profile. We conducted a single arm prospective clinical trial to assess the safety and toxicity of single fraction stereotactic body radiation therapy (SBRT) in the post-operative setting.
Materials/Methods: Eligibility criteria included pathologic N2 disease or close (=2 mm) or positive surgical margins (SM) following surgical resection for NSCLC. A minimum of 3 N2 nodal stations were required to be sampled at surgery. For N2 involvement, patients received 10Gy in a single fraction to the bronchial stump and at-risk nodal stations per the Lung ART trial. In the setting of extra nodal extension (ENE) or close/positive SM, patients received 16Gy in 1 fraction to the at-risk region. Dose constraints were per RTOG 0915 and except for the ribs, OAR constraints took precedence over target coverage. Treatment was delivered using a deep inspiration breath hold.
Results: From December 2019 to September 2024, 48 patients were enrolled. The median follow up was 28.1 months (range = 2.1-60.2). The median age was 68.0 years (range): 50.1-84.6, 16 (33.3%) received neoadjuvant systemic therapy, 42 (87.5%) had N2 disease and 7 (14.6%) had close or positive SM. Among these patients, 3 (6.3%) had ENE present and 9 (18.8%) had multi-station N2 involvement. 41(85.4%) patients received 10Gy in a single fraction and 7 (14.6%) received 16Gy. Within the cohort, there were 10 (20.8%) local,10 (20.8%) regional, and 11 (22.9%) distal failures. The estimated median disease-free (DFS) and overall survival (OS) were 49.3 months and not yet reached respectively. The estimated 3-year DFS and OS were 57.3% and 71.9% respectively. There were 11 (22.9%) grade 1-2 and no grade 3+ treatment related adverse events. The most common grade 2 event was fatigue (n=2).
Conclusion: Single-fraction SBRT in the post-operative setting was well tolerated with comparable oncologic outcomes obtained from conventionally fractionated PORT. Further investigation of single-fraction PORT is warranted.