Cancer Metastasis.
The tumor is a mass of cancer cells from which some cells try to move away and invade the body via the circulatory system. These cells enter and circulate in the blood stream via a process known as Intravasation. These cells are known as Circulating Tumor Cells (CTC).
Circulating Tumor Cells (CTC) have the ability to also get out of the blood stream via Extravasation. Thus, cancers cells can travel from one tissue/organ to another and potentially form a new tumor in the invaded tissue/organ.
This process is known as metastasis and it is responsible for 90% of cancer related deaths worldwide.