1. Is breast cancer prone to brain metastasis? Brain metastases are 30% to 60% from primary lung cancer and 15% to 25% from breast cancer. Thus, after lung cancer, breast cancer is the second most common primary site of brain metastases. With the improvement of breast cancer treatment in recent years, the survival period of breast cancer patients is significantly longer, and the incidence of brain metastases from breast cancer is also increasing. 2. What are the types of breast cancer brain metastases? Where do they usually occur? The most common type of breast cancer brain metastasis is brain parenchymal metastasis, which accounts for 85% to 95%; followed by cancerous meningitis, which accounts for 5% to 15%; the least common is spinal cord dissemination, which accounts for about 1%. The lesions of breast cancer brain parenchymal metastasis are usually at the corticomedullary junction, i.e. the gray-white matter junction. Among them, 80% are distributed in the cerebral hemisphere, 15% in the cerebellum, and 5% in the brainstem. 3. Which breast cancers are prone to brain metastasis? Premenopausal female patients with more extensive lesion invasion and hormone receptor negative patients are prone to CNS metastasis. Specifically, young women (age <50 years), large masses (>5 cm), high histological grade of the primary tumor, estrogen receptor negative, triple negative breast cancer, cytokeratin 5/6 (CK5/6) positive, human epidermal growth factor receptor (Her-2) overexpression, epidermal growth factor receptor (EGFR) high expression, existing lymph node metastasis, existing lung metastasis Brain metastases are more frequently seen.