Small-cell lung cancer brain metastasis: From molecular mechanisms to diagnosis and treatment.

Lung cancer is the most malignant human cancer worldwide, also with the highest incidence rate. However, small-cell lung cancer (SCLC) accounts for 14 % of all lung cancer cases. Approximately 10 % of patients with SCLC have brain metastasis at the time of diagnosis, which is the leading cause of death of patients with SCLC worldwide. The median overall survival is only 4.9 months, and a long-tern cure exists for patients with SCLC brain metastasis due to limited common therapeutic options. Recent studies have enhanced our understanding of the molecular mechanisms leading to meningeal metastasis, and multimodality treatments have brought new hopes for a better cure for the disease. This review aimed to offer an insight into the cellular processes of different metastatic stages of SCLC revealed by the established animal models, and into the major diagnostic methods of SCLC. Additionally, it provided in-depth information on the recent advances in SCLC treatments, and highlighted several new models and biomarkers with promises to improve the prognosis of SCLC.