A retrospective study on stereotactic radiotherapy or whole brain radiotherapy for brain metastases of small cell lung cancer

Purposes Small cell lung cancer (SCLC) frequently results in brain metastases, which significantly impact survival rates. Although whole-brain radiotherapy (WBRT) is the conventional approach, it is associated with neurocognitive side effects. Stereotactic radiotherapy (SRT) offers accurate targeting but lacks established guidelines for managing SCLC's numerous metastases. This research conducted a comparative analysis of SRT, WBRT, and WBRT with a boost (WBRT+Boost) to inform clinical management strategies. Methods A retrospective analysis was conducted involving 337 patients with small cell lung cancer (SCLC) who presented with brain metastases and were treated at Zhejiang Cancer Hospital between 2019 and 2026. The patient groups consisted of those receiving stereotactic radiotherapy (SRT) (n = 95), whole-brain radiotherapy (WBRT) alone (n = 181), and WBRT combined with a boost (WBRT+Boost) (n = 61). The primary endpoints of the study were intracranial progression-free survival (iPFS) and overall survival (OS). Statistical analyses employed Kaplan-Meier curves, log-rank tests, Cox proportional hazards models, and 1:1 propensity score matching (PSM) to control for confounding variables. Results Pre-propensity score matching (PSM), stereotactic radiotherapy (SRT) demonstrated a longer median overall survival (OS) compared to whole-brain radiotherapy (WBRT) alone (13.47 vs. 8.27 months, P = 0.013), although the differences in intracranial progression-free survival (iPFS) were not statistically significant. Following PSM, the differences in OS diminished (e.g., SRT vs. WBRT: 11.77 vs. 8.70 months, P = 0.412), while the combination of WBRT and Boost significantly improved iPFS compared to SRT (8.17 vs. 5.87 months, P = 0.021). Multivariate analysis identified a Karnofsky Performance Status (KPS) of ≥ 90 (hazard ratio [HR], 0.63; P = 0.006) and the presence of synchronous metastases (HR, 0.62; P = 0.013) as factors associated with improved OS. Conversely, the presence of extracranial metastases (HR, 2.24; P < 0.001) and more than three brain lesions (HR, 1.44; P = 0.045) were linked to worse OS. Additionally, immunotherapy administered after radiotherapy was found to be protective. Conclusion Radiotherapy modality did not significantly impact OS, but WBRT+Boost may enhance intracranial control. Immunotherapy integration is critical. Future prospective studies should define optimal strategies and synergy with immunotherapy.