Key messages:

• Cancer can begin anywhere in the body when normal cells become abnormal and grow uncontrollably; these cells may form a tumor.
  
  
• A cancerous tumor is named for the area of the body and the type of cell where it began.
  
  
• Cancer can spread to the lymph nodes and other parts of the body.

Cancer is a group of more than 100 different diseases that can begin almost anywhere in the body. It begins when normal cells begin to change and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous). A benign tumor does not spread to other parts of the body and is rarely life threatening. A malignant tumor, on the other hand invades and destroys nearby tissues and spreads to other parts of the body. Some cancers of blood-forming cells (for example, red blood cells and white blood cells), such as leukemia, myeloma and most types of lymphoma, do not form solid tumors like those found in lung or colorectal cancers.

Cancer is named for the type of cell where it started.

• Cancers that begin in the skin or tissue that covers the surface of internal organs and glands are called carcinomas.
  
  
• Cancers that begin in the connective tissue, such as muscle, fat, cartilage, or bone are called sarcomas.
  
  
• Leukemias are cancers of the body’s blood-forming tissues, such as the bone marrow and spleen.
  
  
• Lymphomas are cancers that begin in the lymphatic system, a network of vessels and glands that help fight infection.

Learn more about specific types of cancer.

Sometimes cancer will spread to the lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes are located in clusters in different parts of the body, such as the neck, groin area, and under the arms. Cancer can also spread from where it began to other parts of the body in a process called metastasis. Even if the cancer has spread, it is still named for the area where it began. For example, if breast cancer spreads to the lungs, it is called metastatic breast cancer, not lung cancer.

Watch a brief video on how cancer begins and spreads to other areas of the body.

Video used with permission from BioDigital Systems.

More Information

Risk Factors

Prevention

Staging

Last Updated: April 02, 2010