Thyroid Nodules and Cancer

Topic Overview

About 5% of thyroid nodules that are found during a physical examination in adults are cancerous.1 Nodules that develop after radiation therapy are more likely to be cancerous. On average, cancer develops 10 to 20 years after radiation therapy. A multinodular goiter is as likely to be cancerous as a single nodule.

Thyroid nodules are less common in children than adults. Although some studies have shown cancerous nodules are more common in children, other studies have found the risk is similar in children and adults.2

There are five types of cancerous nodules.

  • Papillary carcinoma. The most common type grows slowly, especially in people who are younger than 45. With treatment, survival rates are very high, even when the cancer has spread to nearby lymph nodes.
  • Follicular cancer. This is the second most common type of thyroid cancer. Follicular cancer usually responds well to treatment.
  • Medullary carcinoma. This rare type of cancer can be inherited and is harder to treat than papillary carcinoma or follicular cancer. New genetic blood tests can be used to identify people who have a high risk of developing medullary carcinoma. People who test positive, but who do not show any symptoms of thyroid cancer, may choose to have the thyroid gland removed.
  • Undifferentiated or anaplastic carcinoma. These rare types of thyroid cancer are typically seen in older people. Usually, by the time a nodule can be felt, the cancer has spread to nearby lymph nodes or other body parts. These tumors are very difficult to treat.
  • Thyroid lymphoma. This rare type of lymphoma starts in the thyroid gland. It results in an enlarged thyroid gland rather than in a thyroid nodule. It is more common in people who have Hashimoto's thyroiditis than in people who have thyroid nodules.

Related Information



  1. Welker MJ, Orlov D (2003). Thyroid nodules. American Family Physician, 67(3): 559–566.
  2. American Thyroid Association Guidelines Taskforce (2006). Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid, 16(2): 1–33. Also available online:


Author Bets Davis, MFA
Editor Maria Essig
Associate Editor Pat Truman, MATC
Primary Medical Reviewer Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer David C.W. Lau, MD, PhD, FRCPC - Endocrinology & Metabolism
Last Updated April 7, 2009

related physicians

related services

Bon Secours International| Sisters of Bon Secours USA| Bon Secours Health System

This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Privacy Policy. How this information was developed to help you make better health decisions.

© 1995-2010 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.