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Location: Marriott Marquis
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PQA 04 - PQA 04 Palliative Care and Central Nervous System Poster Q&A

2520 - Stereotactic Radiosurgery and Whole Brain Radiotherapy for Germ Cell Tumor Brain Metastases: Practice Patterns and Outcomes

Monday, September 30, 2024
10:45 AM – 12:00 PM ET
Location: Hall C

Screen: 3

C. Gui1, S. Funt2, L. A. Boe3, Y. Yu1, M. Zinovoy1, L. Chen1, Y. Yamada1, L. R. G. Pike1, D. Feldman2, and B. S. Imber1; 1Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 2Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, 3Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY

Purpose/Objective(s): Brain metastases (BM) from germ cell tumors (GCT) are a poor-prognostic feature. Nonetheless, many patients relapsing with GCT BM achieve long-term disease control after salvage therapy, which often combines radiotherapy (RT) and chemotherapy (CT). Historically, whole brain RT (WBRT) has been the standard RT approach to GCT BM. For patients with a limited burden of GCT BM, stereotactic radiosurgery (SRS) is an attractive alternative for preservation of cognitive function. However, minimal data are available to guide the optimal use of SRS. We report our institutional radiotherapeutic outcomes for GCT BM, with a focus on WBRT and SRS alone. Materials/Methods: Male patients with extracranial GCT who received WBRT, with or without SRS boost, or SRS alone for BM relapse between 2005 and 2023 were included. Primary outcomes were overall survival (OS) and intracranial progression (IP) from RT completion. Local progression (LP) and radionecrosis (RN) after SRS were assessed per BM treated with SRS. Associations with outcomes were modeled with Cox regression and competing risk regression, accounting for death. Results: Fifty-nine patients were included. Median age at BM diagnosis was 28 years. Thirty-two patients received WBRT. The median WBRT prescription was 30 Gy in 10 fractions. Twenty-seven patients received SRS to 53 BM. The median SRS prescription was 27 Gy in 3 fractions. Patients who received SRS had fewer BM than those who received WBRT (median 1 vs. 3, p = 0.09). Patterns of RT use in conjunction with CT included: RT with no concurrent CT (19 patients, 8 SRS), RT with concurrent conventional-dose CT (17 patients, 6 SRS), RT with concurrent high-dose CT (13 patients, 7 SRS), and salvage RT for progressing BM initially treated with CT alone (10 patients, 6 SRS). Median follow-up among survivors was 87 months. OS and IP estimates at 4 years were 39% (95% CI 29-54%) and 44% (95% CI 31-56%), respectively. OS and IP were not significantly associated with WBRT versus SRS, nor with the pattern of RT use in conjunction with CT. After SRS alone, OS, IP, LP, and RN estimates at 4 years were 47% (95% CI 31-72%), 50% (95% CI 29-67%), 8% (95% CI 3-18%), and 12% (95% CI 4-24%), respectively. Patients who received SRS to a solitary BM (14 patients, 52%) had significantly better OS (HR 0.21, 95% CI 0.06-0.69, p = 0.01) and IP (HR 0.27, 95% CI 0.09-0.83, p = 0.02), compared with those who received SRS to = 2 BM. Number of BM was not associated with outcomes after WBRT. Conclusion: This analysis includes the largest reported series of GCT BM treated with SRS. Although WBRT has historically been the standard approach to GCT BM, a subset of patients treated with SRS alone can achieve long-term survival and intracranial disease control. SRS provides excellent local tumor control without excessive rates of RN. Caution is advised when considering SRS in patients with multiple BM, given elevated risk of IP and death.