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The ability to invade and metastasize are the defining characteristics of a cancer. Invasion refers to the ability of cancer cells to penetrate through the membranes that separate them from healthy tissues and blood vessels. Metastasis can refer either to the spread of cancer cells to other parts of the body, or to the condition produced by this spread. The English word metastasis (plural, metastases) comes from a Greek word that means "a change." The tumors produced by metastasis are sometimes called secondary tumors. Metastasis is responsible for 90% of the deaths caused by cancer.
Metastasis is a complex multi-step process that begins with changes in the genetic material of a cell (carcinogenesis) followed by the uncontrolled multiplication of altered cells. It continues with the development of a new blood supply for the tumor (angiogenesis), invasion of the circulatory system, dispersal of small clumps of tumor cells to other organs or parts of the body, and the growth of secondary tumors in those sites.
The first step in cancer development is a change or mutation of the DNA in the chromosomes of a cell. Mutations can be triggered by a number of different factors, including:
Other mutations in a cell's DNA occur for reasons that are not yet fully understood.
Author Info: Rebecca J. Frey PhD, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Cancer, 2002This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.
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