Efficacy of First-Line Immunotherapy Combined With Chemotherapy in Extensive-Stage Small Cell Lung Cancer Patients With Different Brain Metastases Status: A Systematic Review and Meta-Analysis

BACKGROUND: This study aims to evaluate the efficacy of first-line immunotherapy combined with chemotherapy in extensive-stage small cell lung cancer (ES-SCLC) patients with differing brain metastasis statuses. METHODS: We conducted a comprehensive search in public databases, such as PubMed, EMBASE, and the Cochrane Library, to identify randomized controlled trials involving ES-SCLC patients, with or without brain metastases, who underwent first-line immunotherapy combined with chemotherapy. The primary outcome measure was progression-free survival (PFS), and the secondary outcome measure was overall survival (OS). RESULTS: Our analysis incorporated seven high-quality randomized controlled trials, encompassing 398 patients with brain metastases and 3,533 without. Among patients without brain metastases, the combination of immunotherapy and chemotherapy led to significantly improved PFS (hazard ratio (HR) = 0.72, 95% confidence interval (CI): 0.62 - 0.84, P < 0.001) and OS (HR = 0.77, 95% CI: 0.67 - 0.88, P < 0.001) in comparison to chemotherapy alone. Conversely, for patients with brain metastases, the addition of immunotherapy to chemotherapy did not result in a significant improvement in PFS (HR = 1.03, 95% CI: 0.66 - 1.61, P = 0.887) or OS (HR = 1.03, 95% CI: 0.82 - 1.31, P = 0.776) when compared to chemotherapy alone. CONCLUSIONS: In ES-SCLC patients without brain metastases, first-line immunotherapy combined with chemotherapy demonstrated improved PFS and OS in contrast to chemotherapy alone. However, patients with brain metastases did not experience similar benefits.