Metastasis

Metastasis (Greek: change of the state) is the spread of cancer from its primary site to other places in the body. Localized spread to lymph nodes is not normally counted as metastasis, although this is a sign of poor prognosis.

Related Topics:
Greek - Cancer - Lymph node - Prognosis

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Cancer cells can break away from a primary tumor, penetrate into lymphatic and blood vessels, circulate through the bloodstream, and grow in a distant focus (metastasize) in normal tissues elsewhere in the body.

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Tumors are classified as either benign or malignant. Malignant tumors can spread by invasion and metastasis while benign tumors cannot (and only grow locally). By definition, the term "cancer" applies only to malignant tumors. Still, some tumors with benign histology can behave as malignant tumors, for example in brain tumors, where treatment has to be as aggressive as with malignant disease.

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Patients diagnosed with cancer want to know whether their disease is local or has spread to other locations. It is the ability to spread to other tissues and organs that makes cancer a potentially life-threatening disease, so there is great interest in understanding what makes metastasis possible for a cancerous tumor.

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Metastatic tumors are very common in late stage of the disease. The spread of metastases may occur via the blood or the lymphatics. Usually sarcomas spread by the hematogenous route, while carcinomas spread by the lymphatic route. The most common places for the metastases to occur are the adrenals, liver, brain and the bones. There is also a propensity for certain tumors to seed in particular organs. For example, prostate cancer usually metastasizes to the bones. Similarly, colon cancer has a tendency to metastasize to the liver. Stomach cancer often metastasizes to the ovary in women, where it forms the Krukenberg tumor.

Related Topics:
Adrenal - Liver - Brain - Bone - Prostate cancer - Ovary - Krukenberg tumor

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When cancer cells spread to form a new tumor, it is called a secondary, or metastatic tumor, and its cells are like those in the original tumor. This means, for example, that if breast cancer spreads (metastasizes) to the lung, the secondary tumor is made up of abnormal breast cells (not abnormal lung cells). The disease in the lung is metastatic breast cancer (not lung cancer).

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Cancer cells may spread to lymph nodes (regional lymph nodes) near the primary tumor. This is called nodal involvement, positive nodes, or regional disease. Cancer cells can also spread to other parts of the body, distant from the primary tumor. Doctors use the term metastatic disease or distant disease to describe cancer that spreads to other organs or to lymph nodes other than those near the primary tumor.

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