To plan the best treatment, your doctor needs to learn the extent (stage) of the disease. Staging is a careful attempt to find out the size of the nodule, whether the cancer has spread, and if so, to what parts of the body.

Thyroid cancer spreads most often to the lymph nodes, lungs, and bones. When cancer spreads from its original place to another part of the body, the new tumor has the same kind of cancer cells and the same name as the original cancer. For example, if thyroid cancer spreads to the lungs, the cancer cells in the lungs are actually thyroid cancer cells. The disease is metastatic thyroid cancer, not lung cancer. For that reason, it's treated as thyroid cancer, not lung cancer. Doctors call the new tumor "distant" or metastatic disease.

Staging may involve one or more of these tests:

• Ultrasound: An ultrasound exam of your neck may show whether cancer has spread to lymph nodes or other tissues near your thyroid.
  
  
• CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of areas inside your body. A CT scan may show whether cancer has spread to lymph nodes, other areas in your neck, or your chest.
  
  
• MRI: MRI uses a powerful magnet linked to a computer. It makes detailed pictures of tissue. Your doctor can view these pictures on a screen or print them on film. MRI may show whether cancer has spread to lymph nodes or other areas.
  
  
• Chest x-ray: X-rays of your chest may show whether cancer has spread to the lungs.
  
  
• Whole body scan: You may have a whole body scan to see if cancer has spread from the thyroid to other parts of the body. You get a small amount of a radioactive substance. The substance travels through the bloodstream. Thyroid cancer cells in other organs or the bones take up the substance. Thyroid cancer that has spread may show up on a whole body scan.

Dictionary Terms

A series of detailed pictures of areas inside the body taken from different angles. The pictures are created by a computer linked to an x-ray machine. Also called CAT scan, computed tomography scan, computerized axial tomography scan, and computerized tomography.

Having to do with metastasis, which is the spread of cancer from the primary site (place where it started) to other places in the body.

A procedure in which radio waves and a powerful magnet linked to a computer is used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques, such as computed tomography (CT) or x-ray. MRI is especially useful for imaging the brain, the spine, the soft tissue of joints, and the inside of bones. Also called magnetic resonance imaging, NMRI, and nuclear magnetic resonance imaging.