Advances in mechanisms and treatments of brain metastases

Statistics indicate that brain metastases occur in nearly 30% of patients with solid tumors, with lung cancer, breast cancer, and melanoma being the three most common primary sources. Brain metastasis is characterized by the co-evolution of tumor cells co-evolve with the brain microenvironment, inducing changes in the phenotype of brain stromal cells that facilitate the colonization, survival, and growth of tumors. The prognosis for brain metastases remains poor, with 2-year and 5-year survival rates for patients diagnosed with brain metastases of 8.1% and 2.4%, respectively. Notably, more than half of brain metastases patients die from neurological diseases. Current treatment options for brain metastases include radiotherapy, neurosurgery, systemic chemotherapy, targeted therapy, and immunotherapy, which are often used in combination to improve therapeutic outcomes. In recent years, the use of nanomaterials for brain metastases treatments has been progressively developed to enhance the efficiency and precision of drug delivery. In the future, with a deeper understanding of the mechanisms underlying brain metastases and further development of treatment strategies, patient outcomes are expected to improve. This review, summarizes the current understanding of brain metastasis mechanisms and therapeutic approaches, and outlines an outlook on future research directions in the field. • Epithelial-mesenchymal transition is a key driver of tumor cell invasion into brain. • Immunosuppressive tumor microenvironment is key for brain metastatic colonization. • Brain metastases treatment includes radiotherapy, targeted therapy and immunotherapy. • Nanomaterials aim to enhance drug delivery across the blood-brain barrier.