File:Colonization of metastatic tumor cells in the brain.jpg

Overexpression of the adhesion molecules makes it easy for tumor cells to target and adhere to endothelial lining in the parenchyma, making it possible for these endothelial-adhesive interactions to enhance the possibility of brain metastasis. Direct neurotropic interactions with brain homing mechanisms result in brain metastases. “Vascular co-option” is the ability of metastatic cells to grow along the preexisting vessels, and once adherent to the vascular basement membrane, tumor cells can extravasate into the parenchyma, the vascular basement membrane thus being the “soil” for brain metastases.