WHAT IS A THYROID MICROCARCINOMA?
A thyroid microcarcinoma is a very small thyroid cancer. It is 1 centimeter (about ½ inch) or smaller. Most thyroid microcarcinomas are papillary thyroid cancers (papillary thyroid microcarcinomas), the most common type of thyroid cancer.
These microcarcinomas are very common. Many people have one and never know it because it does not cause symptoms. They are often found by chance during an imaging test, such as an ultrasound or CT scan, done for another reason. The diagnosis is often made with an ultrasound guided fine-needle biopsy.
Even though hearing the word “cancer” can be frightening, the outlook for most thyroid microcarcinomas is excellent.
Most thyroid microcarcinomas do not grow. If they do grow, they usually grow very slowly.
Over 10 years, the cancer may spread to nearby lymph nodes in:
- About 16 out of 100 people who are 40 or younger
- About 2 out of 100 people ages 41 to 59
- Less than 1 out of 100 people age 60 or older
Your doctor can help explain what these numbers mean for you.

