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NCCN Guidelines for Patients



Thyroid Cancer, Version 1.2017


Thyroid cancer

Thyroid cancer

Normal cells typically stay in one location in the body.

Cancer cells can escape from where they started

and move to other parts of the body. This process is

called metastasis. Cancer cells can travel to distant

parts of the body through the blood or lymphatic

system. When cancer cells settle into new places in

the body they can replace or damage healthy cells.

Thyroid cancer

About 60,000 people a year will be diagnosed with

thyroid cancer in the United States. Statistics show

that more women than men are diagnosed with

thyroid cancer. It is the 4


most common cancer type

found in women.

How this cancer starts

In general, cancer is named after the place where it

starts in the body, and keeps the same name even

if it happens to spread. Thyroid cancer, therefore,

starts in the cells of the thyroid gland.

A biopsy can confirm a diagnosis of cancer. A

sample of fluid or tissue is taken during a biopsy

and examined under a microscope. Since there are

different cells in the thyroid, there are different cell

types of thyroid cancer, which grow and behave

differently in the body.

Your doctor can test for the cell type of thyroid

cancer. This is known as histology. Histology is an

important piece of a cancer diagnosis and helps

your doctors determine how to treat the cancer. A

pathologist will classify the cell type based on the

size, shape, and structure of the cells. A pathologist

is a doctor who is an expert in examining cells and

tissue to find disease.

The cell types for thyroid cancer are:



Papillary, follicular, or Hürthle cell (all




Anaplastic (undifferentiated)




Differentiated cells look similar to normal cells when

examined under a microscope. The most common

type of differentiated thyroid cancer is papillary.

Papillary thyroid cancer is usually very easy to

diagnose through a needle biopsy. Further lab tests,

an additional biopsy, or surgery may be needed

to check for follicular and Hürthle cell carcinoma.

Hürthle cell cancer is uncommon and can be difficult

to diagnose. Papillary, follicular, and Hürthle cell

cancers all come from the same type of cell in the

thyroid, the follicular cell. These three types of thyroid

cancer usually grow and spread slowly.

In contrast, undifferentiated cells look very different

from normal cells under a microscope. Thyroid

cancer with anaplastic cells is undifferentiated and

can grow and spread quickly.

Medullary is a type of thyroid cancer that comes from

the parafollicular cells, or C cells of the thyroid that

make calcitonin. Some people with medullary thyroid

cancer may have other family members who were

diagnosed with this type of thyroid cancer.

Your treatment team will consider your treatment

options based on your histology and stage (extent

of cancer in your body). Doctors use the histology to

decide on the treatment for thyroid cancer. To learn

more about treatment options, see the treatment

guides in Parts 5 through 7 for each type of thyroid