A Population-Based Analysis of Brain Metastasis Burden and Management in 8705 Small Cell Lung Cancer Patients

INTRODUCTION: Patients with small cell lung cancer (SCLC) have historically been characterised by poor overall survival (OS) and high risk for intracranial metastatic disease (IMD), but large-scale real-world evidence on clinical presentation and treatment in this population is lacking. These patients traditionally receive whole brain radiation therapy (WBRT) for IMD, however, a recent systematic review has indicated that OS following stereotactic radiosurgery (SRS) may be non-inferior compared with WBRT. METHODS: We included all patients diagnosed with SCLC between April 2007 and March 2018 identified through a provincial health administrative database. Information on patient and treatment characteristics, incidence and time to IMD, and OS from time of SCLC diagnosis were collected and analyzed using R. RESULTS: A total of 8705 patients were included. Median age was 68 years (range 18-103). Most patients presented with extensive disease (n = 5625) and were diagnosed after 2011 (n = 5768). Patients who received chemotherapy (n = 5563) had significantly longer OS than those who did not (median 10.64 vs 1.58 mo, HR 0.36, 95% CI 0.34-0.37). 6662 patients received brain imaging at the time of primary diagnosis (CT: 5126, MRI: 1536), and 88% of patients surviving longer than 6 mo received more than one follow-up brain scan. 31% developed IMD (synchronous: 1175, asynchronous: 1511) with median intracranial progression-free survival of 5.65 mo. Median OS of patients with IMD was 9.76 mo, 29 and 1300 received SRS and WBRT as first treatment for their IMD, respectively. OS was in favour of SRS over WBRT (median 20.47 vs 8.74 mo, HR 0.57, 95% CI 0.39-0.84), which remained significant in multivariate analysis (p < 0.001). CONCLUSIONS: OS for patients with SCLC remains poor and many patients present with IMD. Some patients with SCLC may benefit from SRS treatment.