Cancer Metastasis

Cancer metastasis refers to the spread of cancer cells to distant locations through the blood or lymphatic system. Experimental evidence has shown that cancer cells are armed with an array of proteolytic enzymes that appear to be essential for the process of cancer dissemination. Cancer metastasis is a complex phenomenon that involves (1) proliferation of cancer cells, (2) survival of immune response, (3) angiogenesis and nutritional supply to the cancer mass, (4) local invasion and destruction, (5) penetration of cancer cells through the blood or lymphatic vessel wall, (6) embolization and clump formation of cancer cells in distant organs and (7) growth of the metastatic cells. The development of metastasis necessitates genetic changes of cancer cells leading to the metastatic phenotype, but the detailed mechanism is not fully understood yet.


Activation of a number of oncogenes has been associated with the invasive, metastatic phenotype in different cancer types. Evidence includes:


Cancer can induce angiogenesis through release of a variety of factors. Vascularization increases the probability of cancer metastasis. The process of angiogenesis involves (1) motility of endothelial cells toward the angiogenic stimulus, (2) proteolysis for penetration of the endothelial cell buds into the extracellular matrix, and (3) proliferation of endothelial cells to form new capillaries.

Metastatic Genes

It is important to know which genes are responsible for the expression of the metastatic phenotype and understand how they are regulated. Some genes actually play a role in suppressing metastasis. The following genes are related to cancer metastasis:

Treatment of Metastasis

Antimetastatic drugs are based on the ideas of inhibiting cancer cell motility, penetration, attachment, or angiogenesis. Drugs working on the genetic level are promising and currently being explored.
Ruddon, R.W. 1995. Cancer Biology. Oxford University Press, New York.