Whole-brain radiotherapy with simultaneous integrated boost in treatment of patients with brain metastases: a systematic review and meta-analysis

PURPOSE: Whole-brain radiotherapy (WBRT) remains the standard treatment for patients with multiple brain metastases (BM), who are not candidates for focal radiotherapy or surgery. A novel approach, WBRT with simultaneous integrated boost (WBRT-SIB), has shown promising results in improving intracranial control and survival compared with WBRT alone. However, no meta-analysis has comprehensively compared those strategies. METHODS/PATIENTS: A systematic review and meta-analysis was performed in accordance with the PRISMA guidelines. Studies indexed up to September 1, 2025, were identified in PubMed, Embase, and Web of Science. Pooled hazard ratios (HRs) were calculated for overall survival (OS), intracranial progression-free survival (iPFS), and intracranial local PFS (iLPFS); odds ratios (ORs) were used for treatment-related adverse events (TRAEs). RESULTS: Thirty studies involving 2,033 patients were analyzed. WBRT-SIB significantly improved OS (HR = 0.7, 95%CI 0.5-0.96, p = 0.03), iPFS (HR = 0.67, 95%CI 0.47-0.96, p = 0.03), and iLPFS (HR = 0.55, 95%CI 0.4-0.79, p < 0.01) compared with WBRT alone. The benefit was mostly driven by patients with small-cell lung cancer (SCLC) (HR = 0.54, 95%CI 0.31-0.92, p = 0.025), while no significant effect was observed for other tumor types. Median OS after WBRT-SIB was 16.78 months, iPFS was 13.07 months, and the objective response rate was 69.5%. WBRT-SIB did not increase the risk of TRAEs, and the incidence of radiation necrosis was 5.05% (95%CI 1.19%-10.77%). CONCLUSION: WBRT-SIB improves intracranial control and may improve overall survival compared with WBRT alone, mostly in patients with SCLC, achieving high response rates with acceptable safety. These results support further investigation of WBRT-SIB for patients with BM who are not candidates for stereotactic radiosurgery.