S881
Clinical - Mixed sites & palliation
ESTRO 2026
drivers in EGFR, ALK or ROS-1. For the majority (87%) of treatment courses, extracranial disease was either controlled, pending assessment after recent systemic therapy initiation, or absent. 76% of SRS courses were prescribed at the time of first-line systemic therapy. 84% of treated lesions were intact BM, and 16% were surgical cavities. Single-fraction SRS was most commonly prescribed (60%) (Table 1). The median follow-up was 31.1 months (range 2.5-56.5). Actuarial estimates for LC at 12, 24 and 36 months were 99%, 96% and 94%, respectively. The 12, 24 and 36-month DFFS were 58%, 46% and 34%, respectively, and the corresponding estimates for OS were 81%, 59% and 42% (Figure 1A). Favourable prognostic factors for OS include controlled or absent extracranial disease (p<0.001), and single BM in the NSCLC subgroup (p=0.008) (Figures 1B, 1C). First-line systemic therapy at SRS was associated with better DFFS (p=0.02) (Figure 1D). The crude incidence of grade 2 and grade 3 radionecrosis were 5% and 2%, respectively. The actuarial estimates for symptomatic radionecrosis at 12 and 24 months were 8% and 18%, respectively.
Conclusion: Long term outcomes on single-isocenter linac-based SRS for BM demonstrate excellent LC and OS with low incidence of toxicity in a contemporary Chinese cohort with high prevalence of actionable oncogenic drivers. References: 1. Brown PD, Jaeckle K, Ballman KV, et al. Effect of Radiosurgery Alone vs Radiosurgery With Whole Brain Radiation Therapy on Cognitive Function in Patients With 1 to 3 Brain Metastases: A Randomized Clinical Trial. JAMA 2016;316:401-9.2. Yamamoto M, Serizawa T, Shuto T, et al. Stereotactic radiosurgery for patients with multiple brain metastases (JLGK0901): a multi- institutional prospective observational study. Lancet Oncol 2014;15:387-953. Palmer JD, Sebastian NT, Chu J, et al. Single-Isocenter Multitarget Stereotactic Radiosurgery Is Safe and Effective in the Treatment of Multiple Brain Metastases. Adv Radiat Oncol. 2019 Sep 16;5(1):70-76. Keywords: Stereotactic radiosurgery, brain metastasis REIRRADIATION OF BRAIN METASTASES: EXPERIENCE OF A HIGH-VOLUME CENTER. Miriam Torrisi 1 , Andrei Fodor 1 , Monica Vincenzi 2 , Laura Giannini 1 , Chiara Lucrezia Deantoni 1 , Roberta Tummineri 1 , Sara Broggi 2 , Lucia Perna 2 , Carmen Gigliotti 2 , Claudio Fiorino 2 , Antonella Del Vecchio 2 , Nadia Di Muzio 1,3 1 Radiation Oncology, IRCCS Ospedale San Raffaele, Milano, Italy. 2 Medical Physics, IRCCS Ospedale San Raffaele, Milano, Italy. 3 Radiation Oncology, Università Vita Salute San Raffaele, Milano, Italy Digital Poster 2320
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