摘要Objective::This retrospective study aims to explore the risk factors for brain metastasis and the prognostic factors for overall survival (OS) in patients with limited-stage small-cell lung cancer (LS-SCLC) who have no brain metastases according to magnetic resonance imaging (MRI) and have not received prophylactic cranial irradiation (PCI) after first-line chemoradiotherapy.Methods::A total of 107 patients who were treated in the Fourth Hospital of Hebei Medical University from January 2013 to December 2017 were enrolled in this study. The patients were treated with etoposide/platinum chemotherapy and thoracic radiotherapy (TRT) with involved-field irradiation. The median dose of the radiotherapy was 60 Gy (50-64 Gy). The primary study endpoints include BMFS (brain-metastasis-free survival) and OS (overall survival). The Kaplan-Meier method was applied to estimate survival, with a log-rank test used to ascertain statistical significance. The multivariate Cox proportional hazards model was used to determine the prognostic factors for survival.Results::The median follow-up of all patients was 18.8 months (range: 7.9-65.1 months) and the median follow-up of surviving patients was 26.7 months (range: 18.8-65.1 months). The median OS of the whole cohort was 20.1 months, and the 1-, 2- and 3-year OS rates were 84.9%, 44.9%, and 25.9%, respectively. The 1-, 2-, and 3-year BMFS rates were 69.0%, 49.9%, and 40.7%, respectively. 50 patients (46.7%) developed brain metastases during the follow-up period, and the median time from the start to brain metastasis was 10.7 months (range: 4.8-31.1 months). As shown by multivariate analysis, independent prognostic factors of OS included cycles of chemotherapy ( P = 0.019), the response to initial treatment ( P = 0.011), and the start time of TRT ( P = 0.044). The independent prognostic factors of BMFS included the clinical stage ( P = 0.008), the response to initial treatment ( P = 0.024), and the start time of TRT ( P = 0.028). Conclusions::For patients with LS-SCLC who have not received PCI, favorable factors for lower brain metastasis and higher survival include early clinical stage, CR to initial chemoradiotherapy, early TRT, and adequate cycles of chemotherapy. PCI is still recommended as the standard modality since the incidence of brain metastases was high (46.7%).