In English | En español
Questions About Cancer? 1-800-4-CANCER

What You Need To Know About™

Thyroid Cancer

  • Posted: 05/07/2012

Page Options

  • Print This Page
  • Print This Document
  • View Entire Document
  • Email This Document
  • View/Print PDF
  • Download to Kindle
  • Download to other E-readers

Cancer Cells

Cancer begins in cells, the building blocks that make up tissues. Tissues make up the thyroid and other organs of the body.

Normal thyroid cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they die, and new cells take their place.

Sometimes, this process goes wrong. New cells form when the body does not need them, and old or damaged cells do not die as they should. The buildup of extra cells often forms a mass of tissue called a nodule. It may also be called a growth or tumor.

Most thyroid nodules are benign. Benign nodules are not cancer (malignant):

  • Benign nodules:
    • Are usually not harmful
    • Don’t invade the tissues around them
    • Don’t spread to other parts of the body
    • Usually don’t need to be removed
  • Malignant nodules (thyroid cancer):
    • May sometimes be a threat to life
    • Can invade nearby tissues and organs
    • Can spread to other parts of the body
    • Often can be removed or destroyed, but sometimes thyroid cancer returns

Thyroid cancer cells can spread by breaking away from the thyroid tumor. They can travel through lymph vessels to nearby lymph nodes. They can also spread through blood vessels to the lungs, liver, or bones. After spreading, cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues.

See the Staging section for information about thyroid cancer that has spread.

This text may be reproduced or reused freely. Please credit the National Cancer Institute as the source. Any graphics may be owned by the artist or publisher who created them, and permission may be needed for their reuse.