Improvements in the diagnosis and treatment of systemic breast cancer have led to a prolongation in patient survival. Unfortunately, these advances are also associated with an increased incidence of brain metastases (BM), with the result that many patients succumb due to BM treatment failure. Intracranial delivery of many chemotherapeutic agents and other therapeutics is hindered by the presence of an impermeable blood-brain barrier (BBB) designed to protect the brain from harmful substances. The formation of BM compromises the integrity of the BBB, resulting in a highly heterogeneous blood-tumor barrier (BTB) with varying degrees of vascular permeability. Here, we discuss how blood vessels play an important role in the formation of brain micrometastases as well as in the transformation from poorly permeable BM to highly permeable BM. We then review the role of BTB vascular permeability in the diagnostics and the choice of treatment regimens for breast cancer brain metastases (BCBM) and discuss whether the vasculature of primary breast cancers can serve as a biomarker for BM. Specifically, we examine the association between the vascular permeability of BCBM and their accumulation of large molecules such as antibodies, which remains largely unexplored.

全身性乳腺癌诊断和治疗的改进已导致患者生存期的延长。不幸的是，这些进展也与脑转移 (BM) 发生率的增加有关，导致许多患者因 BM 治疗失败而死亡。许多化学治疗剂和其他治疗剂的颅内给药受到旨在保护大脑免受有害物质侵害的不可渗透血脑屏障 (BBB) 的存在的阻碍。BM 的形成损害了 BBB 的完整性，导致具有不同程度血管通透性的高度异质性血肿瘤屏障 (BTB)。在这里，我们讨论血管如何在脑微转移的形成以及从低渗透性 BM 到高渗透性 BM 的转变中发挥重要作用。然后，我们回顾了 BTB 血管通透性在乳腺癌脑转移 (BCBM) 诊断和治疗方案选择中的作用，并讨论了原发性乳腺癌的血管系统是否可以作为 BM 的生物标志物。具体来说，我们检查了 BCBM 的血管通透性与其大分子（如抗体）积累之间的关联，这在很大程度上仍未得到探索。