Interactions between cancer cells and the microvasculature: a rate-regulator for metastasis.

Hematogenous metastasis is a major consideration in the staging, treatment and prognosis of patients with cancer. Key events affecting hematogeneous metastasis occur in the microvasculature. This is a brief, selective review of some interactions involving cancer cells and the microvasculature in pathologic sequence, specifically: (1) intravasation of cancer cells; (2) the arrest of circulating cancer cells in the microvasculature; (3) cancer cell trauma associated with arrest; (4) microvascular trauma; (5) the inflammatory; and (6) the hemostatic coagulative responses associated with arrest, and finally (7) angiogenesis, leading to tumor vascularization. The evidence shows that through a series of complex interactions with cancer cells, the microvasculature acts as a rate-regulator for the metastatic process, in addition to providing routes for cancer cell dissemination and arrest sites for cancer cell emboli.