NCCN Guidelines for Patients
Thyroid Cancer, Version 1.2017
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.
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
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