CAMBRIDGE, Mass-- Cancer cells metastasize in several stages -- first by invading surrounding tissue, then by infiltrating and spreading via the circulatory system. Some circulating cells work their way out of the vascular network, eventually forming a secondary tumor.
While the initial process by which cancer cells enter the bloodstream -- called intravasation -- is well characterized, how cells escape blood vessels to permeate other tissues and organs is less clear. This process, called extravasation, is a crucial step in cancer metastasis.