This study is a multicenter, randomized, prospective Phase III study to evaluate the efficacy and safety of anlotinib plus whole-brain radiotherapy (WBRT) compared with WBRT alone in small cell lung cancer (SCLC) patients with brain metastases. Additionally, by investigating the association between changes in circulating tumor cell (CTC) levels in peripheral blood and treatment response to the combination of targeted therapy and radiotherapy, we aim to identify a patient subgroup most likely to benefit from this regimen, as well as potential biomarkers predictive of treatment efficacy.