Cancer is the general name for more than 100 diseases characterized by uncontrolled cell growth. Normal cells follow a path of growth, division and death. Cancer cells, on the other hand, continue to divide when new cells are not needed. This uncontrolled cell growth leads to a mass or growth of tissue that is called a tumor (except in the cancers known as leukemia, in which cancer interferes with normal blood function by abnormal cell division in the blood stream).
Not all tumors are cancerous. Some tumors—benign tumors—are not cancerous and can be removed, and in most cases do not come back. Malignant tumors, however, are cancerous, and their cells can enter the bloodstream and spread throughout the body invading and destroying healthy tissue. This spreading from one part of the body to another is called metastasis.
Cancer is named for the place where it started—what’s called the primary site. No matter your cancer, it may spread to other parts of your body, so cancer that has metastasized is still named for its place of origin. For example, if breast cancer spreads to the liver, it is called “metastatic breast cancer,” not liver cancer.
If your cancer is not listed here, please visit the NCI website and search for additional information about your specific cancer.