What is thyroid cancer?

Thyroid cancer is a malignant growth that develops from thyroid cells. As new thyroid cells are produced, certain cells may become abnormal. When these abnormal cells continue to multiply and expand in an uncontrolled fashion, they become a tumor. If a tumor grows but remains contained within itself and does not spread to invade normal tissue, it is considered to be benign. If it grows and spreads to normal tissue, it is considered to be malignant or cancerous.

For More Information
EndocrineWeb.com
National Institutes of Health, National Cancer Institute
ThyCa: Thyroid Cancer Survivor's Association, Inc.