2675 - Radiation Necrosis Management and Outcome in Patients with NSCLC Brain Metastases Treated with SRS in the Era of Immunotherapy
Presenter(s)
S. S. Varghese1, Y. Cao1, S. Zahid2, P. Markley3, J. Manning4, S. Yiqing5, Y. Hou1, T. Stepp6, and F. Wang7; 1Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS, 2Kansas City University, Kansas city, KS, 3The University of Kansas, School of Medicine, Kansas city, KS, 4The University of Kansas, School of Medicine, Kansas City, KS, 5Department of Radiation Oncology, The University of Kansas Medical center, Kansas City, KS, 6Department of Neurosurgery, The University of Kansas Medical center, Kansas City, KS, 7Department of Radiation Oncology, The University of Kansas Medical Center, Kansas City, KS
Purpose/Objective(s): Radiation necrosis (RN) is a significant adverse effect of SRS for brain metastases. The improved survival of patients with brain metastases and increased use of immunotherapy in NSCLC contributed to the growing incidence of necrosis. This study aimed to assess the incidence, management, and outcome of patients who developed RN after SRS for NSCLC brain metastases.
Materials/Methods: From June 2009 to August 2023, 296 patients with NSCLC brain metastases were treated with SRS at our center. We reviewed the charts of these patients and identified those who developed RN on follow-up imaging. We collected data on the total number of SRS treatments, the total volume of lesions treated, and the PD-L1, EGFR, ALK, and ROS status, and systemic therapy. Additionally, we recorded the time to develop RN after SRS, the treatment of RN, the outcome of RN, and the overall survival (OS) of these patients. The OS was calculated from the date of the first SRS to the date of death or the last follow-up. Descriptive statistics were used to analyze this data.
Results: Of the 296 patients, 98 received immunotherapy or targeted therapy during their treatments. The median length of follow-up was 23 months (range: 1 – 126). The median OS of the entire cohort (n=296) was 8.7 months. The median OS of those who received Immunotherapy/targeted therapy was 14.5 months compared to 6.7 months for those who did not. The median number of SRS treatments per patient was 1 (1-6). The median age at the time of SRS was 62.8 years (34.8 - 76.8). The median SRS dose was 20 Gy, and the median PTV was 8.88 cc (range: 0.35 - 94.90). 5/50 patients underwent salvage whole brain RT. 50 patients (17%) developed radiation necrosis during follow-up. The median OS of the patients who developed RN was 31 months. 37/50 patients received immunotherapy or targeted therapy during their treatment developed RN earlier (8.6 mo.) but better OS of 31.3 mo. than those did not received immunotherapy or targeted therapy (11 mo.) and OS of 20.9 mo. 25/ 50 patients received Bevacizumab for necrosis, one had LITT, and four had surgical resection. The median OS for patients who received Bevacizumab was 44 months, compared to 18 months for those who did not. During follow-up, 10 patients experienced resolution of necrosis, 17 had stable RN, and 23 had progressive RN. Among the 10 patients with necrosis resolution, 7 received Bevacizumab. At the time of this analysis, 12/50 patients were alive. All 38 patients who died had extracranial ± intracranial disease progression.
Conclusion: Our study demonstrates that patients developed RN after SRS in NSCLC with brain metastasis shows a trend towards improved OS. Treatment of RN with Bevacizumab also improves the resolution of necrosis and OS.