Stereotactic Radiosurgery for Multiple Brain Metastases: from Rationale to Clinical Practice

Abstract

Relevance : Multiple brain metastases (BM) remain one of the central clinical challenges in neuro-oncology. Advances in systemic therapy and the widespread use of MRI have increased the detection of intracranial progression and required a re-evaluation of local treatment strategies, in which tumor control must be balanced against preservation of cognitive function and quality of life. Purpose : To synthesize current evidence on stereotactic radiosurgery (SRS) in adults with multiple BM, to clarify the evidence supporting SRS without whole-brain radiotherapy (WBRT), and to evaluate dosimetric aspects, cognitive outcomes and patient selection criteria. Materials and methods : A literature search was performed in PubMed/MEDLINE, Ovid and the Cochrane Library covering the period from January 2010 to April 2026. Eligible publications included original clinical studies, systematic reviews, meta-analyses, clinical guidelines and topical reviews addressing SRS/SRT in adults with multiple (predominantly ≥5) BM. This is a narrative review with a structured search; no protocol was registered, and PRISMA flow, formal risk-of-bias assessment and meta-analysis were not performed. Results : Accumulated evidence indicates that the absolute number of intracranial lesions is not a sufficient criterion for SRS eligibility. In patients with 5–10 BM meeting JLGK0901 inclusion criteria, overall survival and complication rates are comparable to those with 2–4 lesions. For >10 BM the evidence base is weaker and mostly retrospective, yet SRS remains clinically justified in carefully selected patients with limited total tumor volume, preserved performance status and controlled systemic disease. The principal constraint in multiple BM is not the lesion count but the total tumor volume and dosimetric feasibility, with V 12 (single-fraction SRS) and V 20 /V 24 (3- and 5-fraction SRT) as key planning parameters. Conclusion : SRS for multiple BM should be regarded as a selective local strategy, the appropriateness of which is determined by the combination of treatment feasibility (total tumor volume, dosimetric constraints) and clinical rationale (GPA-based survival prognosis, control of extracranial disease, availability of systemic therapy). A local-only strategy is justified only when pre-planned MRI surveillance and timely salvage options are available.