Metastasis

Metastasis refers to the spread of cancer. Usually, this happens as cancer cells break away from a primary tumor and enter the bloodstream or lymphatic system. When cancer cells spread and form a new tumor in a different organ, the new tumor is a secondary or metastatic tumor (1). Cancer cells can spread to almost any part of the body, though some areas are more prone to the spread of cancer. The lymph nodes near the primary tumor are especially vulnerable, and if cancer spreads to the nearby lymph tissue, it is termed regional disease. When cancer spreads to other organs or to lymph nodes far from the primary tumor, it is termed metastatic disease (2).

The most common sites of metastasis from solid tumors (as opposed to non-solid tumors, such as leukemias) are the lungs, bones, liver, and brain. Some cancers tend to spread to certain specific parts of the body over others. For example, lung cancer often metastasizes to the brain or bones, and colon cancer frequently spreads to the liver (2, 3).

The cells in the metastatic tumor originate from the primary tumor. For example, if lung cancer metastasizes in the brain, the brain tumor cells will appear similar to diseased lung cells and not diseased brain cells. Thus, upon the examination of tumor cells under a microscope, pathologists are able to determine whether the site of a tumor is the primary site or the result of a metastasis (2).

Metastatic cancers may be found at the same time as the primary tumor, months or years later, or even before the primary cancer is discovered. In some cases, an individual's primary cancer is discovered only after the metastic tumor causes noticeable symptoms. When a new tumor is found in a patient who has previously been treated for cancer, it is more often a metastasis than another primary tumor (2).

'Metastasis' Sources:
  1. "Metastasis." From Medterms.com. Available: http://www.medterms.com/script/main/art.asp?articlekey=4363 (Accessed August 20, 2007).
  2. "Metastatic Cancer: Questions and Answers." From the National Cancer Institute's website. Available: http://www.cancer.gov/cancertopics/factsheet/Sites-Types/metastatic (Accessed August 20, 2007).
  3. "Young People with Cancer: A Handbook for Parents." From the National Cancer Institute and the National Institutes of Health. Available: http://www.cancerlinksusa.com/cancer/young/solidtumor.htm (Accessed August 20, 2007).




 

 

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