2400 - Practice Variations and Outcomes of Definitive Radiation for Non-Metastatic NSCLC following Induction Chemoimmunotherapy
Presenter(s)
T. Kleber1, S. H. Lin1, S. A. Copling2, A. Kim2, T. Cascone3, C. M. Gay4, W. Rinsurongkawong5, V. Rinsurongkawong6, J. J. Lee7, J. Zhang5, D. L. Gibbons4, A. A. Vaporciyan8, J. Heymach5, and J. K. Bronk9; 1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 2McGovern Medical School, Houston, TX, 3University of Texas MD Anderson Cancer Center, Houston, TX, 4Department of Thoracic-Head & Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 5Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 6The University of Texas MD Anderson Cancer Center, Houston, TX, 7MD Anderson Cancer Center, Houston, TX, 8Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX, 9Department of Thoracic Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose/Objective(s): The use of induction chemoimmunotherapy prior to the definitive treatment of locally advanced non-small cell lung cancer (NSCLC) is emerging as a standard of care approach. While the outcomes of this regimen in surgical patients have been well-documented, limited data exist regarding the use of induction chemoimmunotherapy followed by definitive radiation. Herein, we report the various radiation regimens used in this context as well as treatment side effects and outcomes.
Materials/Methods: In an IRB-approved protocol, we retrospectively reviewed patients at our institution with NSCLC treated with induction chemoimmunotherapy with stable response or better followed by definitive radiotherapy. Exclusion criteria included stage IV disease at diagnosis or prior history of systemic therapy or radiotherapy for NSCLC. Patient characteristics, treatment details, toxicities, and clinical outcomes were recorded for each patient. Progression free survival (PFS) and overall survival (OS) were measured from radiation completion and reported with 95% confidence intervals (CI). Comparisons between treatment cohorts were performed using fisher’s exact tests, with significance defined as p < 0.05.
Results: Of the 49 patients identified, 23 (47%) were male, 47 (96%) had a history of tobacco use, 29 (59%) had = 1% PD-L1 expression, and median age at radiation start was 68. Patients completed a median of 3 cycles of induction chemoimmunotherapy between 2017 and 2024. Following induction therapy, 30 patients (61%) received concurrent chemoradiation (CRT) in 27-30 fractions, 14 (29%) received hypofractionated radiotherapy (HRT) without chemotherapy in 15-25 fractions, and 5 (10%) received stereotactic body radiation therapy (SBRT) in 4-5 fractions. 86% of patients who received HRT had stage III disease, which was higher than those who received CRT (70%) or SBRT (20%) with statistical significance (p = 0.015). 67% of patients who received CRT subsequently started maintenance immunotherapy, which was higher than those who received HRT (36%) or SBRT (40%) without statistical significance (p = 0.15). Among patients who received CRT, HRT, and SBRT, 12-month OS rates were 84% (95% CI, 71%-100%), 58% (36%-94%), and 100% (100%-100%), 12-month PFS rates were 61% (45%-84%), 51% (29%-89%), and 75% (43%-100%), and overall local control rates were 93%, 83%, and 100%, respectively. Post-treatment symptomatic pneumonitis that was at least possibly related to radiation occurred in 33%, 21%, and 20% of patients treated with CRT, HRT, and SBRT, respectively.
Conclusion: For stage I-III NSCLC patients with unresectable disease following induction chemoimmunotherapy, definitive radiation alone approaches may be a reasonable alternative to CRT to limit risk of pneumonitis and duration of treatment while maintaining promising clinical outcomes. Further studies are needed to compare radiation regimens in this context.