Prophylactic Cranial Irradiation Versus Active MRI Surveillance in Small Cell Lung Cancer: Systematic Review and Meta-Analysis

Background: Prophylactic cranial irradiation (PCI) has traditionally been a cornerstone of treatment in limited-stage and extensive-stage small cell lung cancer (SCLC). Recent evidence suggests that active MRI brain surveillance may result in comparable overall survival (OS) and progression-free survival (PFS). This systematic review and meta-analysis aims to compare patient outcomes between PCI and active MRI brain surveillance. Method: Medline, Embase, Cochrane Library, Scopus and Web of Science databases were searched from inception until 30th April 2025 to identify all studies comparing PCI against active MRI brain surveillance in adult SCLC patients. Risk ratios (RR) and hazard ratios (HR) were pooled and analysed using a random-effects model. Result: Fourteen studies comprising 2881 patients were included. In patients with limited-stage SCLC, PCI significantly improved OS (HR 0.67, 95% CI 0.53–0.84, p < 0.01), PFS (HR 0.77, 95% CI 0.65–0.91, p < 0.01), and brain metastasis (BM) incidence (RR 0.58, 95% CI 0.45–0.76, p < 0.01). In patients with extensive-stage SCLC, PCI only significantly reduced BM risk (RR 0.49, 95% CI 0.29–0.81, p < 0.05), but was not associated with significant improvement in OS (HR 0.89, 95% CI 0.61–1.28, p = 0.52) or PFS (HR 0.90, 95% CI 0.60–1.36, p = 0.62). Conclusion: While PCI reduces BM incidence in both limited-stage and extensive-stage SCLC, its survival benefits are confined to limited-stage SCLC. Active MRI brain surveillance may be preferred in extensive-stage disease due to comparable survival outcomes and reduced toxicity. Trial Registration: CRD42024529707 [PROSPERO]. © 2026 The Author(s). Journal of Medical Imaging and Radiation Oncology published by John Wiley & Sons Australia, Ltd on behalf of Royal Australian and New Zealand College of Radiologists.