2676 - Stereotactic Radiosurgery for 15 or More Brain Metastases is Safe and Effective

08:00am - 09:00am PT

Hall F

Screen: 9

POSTER

Presenter(s)

Tina Vaziri, MD - Johns Hopkins Hospital, Baltimore, MD

T. L. Vaziri¹, I. C. Liu¹, C. Bettegowda¹, V. J. Croog¹, C. Jackson¹, D. Kamson², L. R. Kleinberg¹, C. Kut¹, D. Mukherjee³, J. Rincon Torroella⁴, B. R. Page¹, R. Xu³, and K. J. Redmond¹; ¹Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, ²The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, ³Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, ⁴Johns Hopkins, Baltimore, MD

Purpose/Objective(s): Stereotactic radiosurgery (SRS) has become standard of care for patients with limited brain metastases (BM), offering superior neurocognitive outcomes compared to whole-brain radiation therapy (WBRT). As advancements in cancer therapies have extended survival in metastatic disease, the question remains regarding the benefit of SRS in those with high intracranial disease burden. To explore this, we analyzed our institutional experience of patients treated with SRS to 15 or more BMs over their disease course.

Materials/Methods: This IRB-approved, single-institution retrospective study analyzed patients with at least 15 SRS-treated BMs between 1/1/2010 and 12/31/2023. Baseline patient and disease characteristics, SRS details, and radiation-related toxicities were summarized using descriptive statistics. Clinical endpoints included freedom from WBRT (FFW), freedom from neurological death (FFN), and overall survival (OS), defined from the time of the 1^st SRS course. Clinical factors associated with the endpoints were assessed through Cox proportional hazards models.

Results: Ninety patients were included in the analysis. The median number of BMs treated and SRS courses per patient were 18 (range, 15-32) and 2 (range, 1-8), respectively. The primary sites of malignancy were lung (47.3%) or breast (22.6%). At the time of the 1^st SRS course, 80 patients (84.9%) had an ECOG 0-1 or KPS >70, and 30 (33%) had neurologic symptoms with/without hospitalization. Notably, 25 patients (28%) had newly diagnosed disease, while 30 patients (33.3%) had controlled extracranial disease. With a median follow up of 15 months (range, 0-118 months), radiation necrosis was reported in 9 patients (10%), 16 (17.2%) were hospitalized for neurologic symptoms within 30 days of SRS, and 12 (13.2%) developed leptomeningeal disease (median time from 1^st SRS: 12.7 months). The mean summed dose to the whole brain after all SRS courses was 5.28 Gy. Median and 1-year OS was 27.8 months and 63.2%, respectively. 1-year FFN was 87.3%. Excluding patients that received prophylactic cranial irradiation (PCI) or WBRT prior to SRS, 1-year FFW was 70.8%. After the 1^st course of SRS, the median time to intracranial progression and salvage therapy (i.e. additional SRS course, WBRT, or surgery) were 4.1 and 5.3 months, respectively. On univariate analysis, patients with 15 or more BMs treated in their 1^st SRS course had shorter FFW (HR 2.84; 95% CI 1.1-7.1) and shorter OS (HR 2.72; 95% CI 1.6-4.7).

Conclusion: Our findings support the use of SRS in patients with a large number of BMs to delay WBRT with the intent of preserving cognitive function and quality of life. The integral dose to the whole brain was low and far below constraints that may be achieved to the hippocampus when treating with hippocampal avoidance WBRT. Multi-institutional and prospective data are needed to further explore the safety and efficacy of this approach.