Definition
What is metastasis?
Metastasis is how a cancer moves beyond the place where it began. Cells break away from the primary tumor, travel through the bloodstream or lymphatic system and start new growths, called metastases or secondary tumors, in other tissues. The ability to metastasize is what most clearly separates malignant tumors from benign ones, and metastatic disease causes most cancer deaths.
Spreading takes several steps. Cancer cells invade nearby tissue, squeeze through the walls of small blood or lymph vessels, survive the journey in the circulation, lodge in a distant capillary, push out into the new tissue and multiply. To grow beyond a tiny cluster, the new tumor must also trigger angiogenesis, the sprouting of blood vessels to feed it. Most escaping cells die on the way, and some survivors lie dormant for years.
A secondary tumor keeps the identity of the original cancer: colon cancer that has reached the liver is still colon cancer, made of colon cells, not liver cancer. Bone, liver, lung and brain are frequent sites. Cancer with distant spread is usually classed as stage 4.
Word parts
Where does the word “metastasis” come from?
- meta-
- change of place or stateGreek meta
- stasis
- standing, positionGreek stasis
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Terms that go with it
- Malignant tumorA malignant tumor is a cancerous mass whose cells grow without control, invade surrounding tissue and can spread to distant organs.
- CancerCancer is a group of diseases in which abnormal cells divide without control, invade nearby tissue and can spread to distant parts of the body.
- TumorA tumor is an abnormal mass of tissue made by cells that multiply too much or fail to die on time; it can be benign or malignant.
- CarcinomaA carcinoma is a cancer that starts in epithelial cells, the cells that cover the skin and line the inner and outer surfaces of organs.
- ChemotherapyChemotherapy is the treatment of cancer with drugs that kill rapidly dividing cells or stop them from multiplying, usually given in repeated cycles.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- NCI Dictionary of Cancer Terms: metastasis
- National Cancer Institute: Metastatic Cancer
- Cancer Research UK: How cancer can spread
- WHO Fact Sheet: Cancer
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