Modern therapies: Nanotechnology promises new approaches for rare breast cancer brain metastases

Brain metastasis originating from breast cancer is an uncommon but clinically significant complication that poses substantial therapeutic challenges and is associated with poor patient prognosis. Traditional treatment modalities-including surgical resection, whole-brain radiation therapy, stereotactic radiosurgery, and systemic chemotherapy-often fail to achieve satisfactory long-term control due to the protective nature of the blood-brain barrier (BBB), tumor heterogeneity, and the aggressive biology of metastatic lesions. This comprehensive review delves into recent advances in modern therapeutic approaches that aim to enhance the efficacy of conventional treatments for rare brain metastases from breast cancer (BC). We systematically evaluate emerging strategies such as advanced drug delivery technologies, including nanoparticles (NPs), polymeric NPs, and liposomal formulations, which are designed to overcome pharmacokinetic limitations and improve the penetration and retention of chemotherapeutic agents within the central nervous system (CNS). The review also explores the integration of immunotherapies, particularly immune checkpoint inhibitors and adoptive cell therapies-with traditional modalities to potentiate antitumor immune responses in the brain microenvironment. Moreover, we discuss the development and application of novel radiosensitizers and combination regimens aimed at overcoming the inherent and acquired radioresistance of metastatic tumors. The synthesis of current preclinical models and clinical trial data provides critical insights into the potential of these combined approaches to enhance patient survival and quality of life. Finally, we identify key challenges, including the need for personalized treatment protocols and the management of therapy-related toxicities, and propose future directions for research.