What does stage of cancer mean?

The stage of a cancer is how much and how far the cancer has spread in your body. Your healthcare provider uses exams and tests to find out the size of the cancer and where it is. Your provider can also see if the cancer has grown into nearby areas, and if it has spread to other parts of your body. The stage of a cancer helps determine how serious it is and is one of the most important things to know when deciding how to treat the cancer.

With thyroid cancer, your provider may need to remove your thyroid with surgery before they know the cancer's stage. The stages of thyroid cancer differ. They depend on the type of cancer you have. For certain types of thyroid cancer, your age is also a factor. Here is a summary of the stages for different types of this cancer.

The TNM system for thyroid cancer

The most commonly used system to stage thyroid cancer is the TNM system from the American Joint Committee on Cancer. Staging is very complex. Be sure to ask your healthcare provider to explain the stage of your cancer to you in a way you can understand.

The first step is to find the value for each part of the TNM system. Here's what the letters stand for in the TNM system:

• T tells how far the main tumor has grown in the thyroid and spread into nearby tissue. The tumor is measured in centimeters (cm).

• N tells if the lymph nodes near the primary tumor have cancer in them.

• M tells if the cancer has spread ( metastasized) to distant areas of the body, like the lungs. bones, or brain.

Numbers or letters after T, N, and M provide more details about each of these factors. There are also two other values that can be assigned:

• X means the provider does not have enough information to tell the extent of the primary tumor, or if the lymph nodes have cancer cells in them.

• 0 means no sign, such as no sign of cancer in lymph nodes (N0).

The T, N, and M values from the TNM system are used to put these cancers into stage groupings. These groupings give an overall description of your cancer. A stage grouping can have a value of 0 or Roman numerals I (1), II (2), III (3), or IV (4). The higher the number, the more advanced your cancer is.

What are the stages of papillary and follicular thyroid cancers?

Age is a part of staging for these types of cancers.

If you are younger than 55:

• Stage I. The tumor may be any size. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

• Stage II. The tumor may be any size. It may or may not have spread to nearby tissues and lymph nodes. It has spread to distant sites of the body.

If you are age 55 or older:

Stage I. The tumor is small (4 cm or less) and is still in the thyroid. It has not spread to nearby lymph nodes or to distant parts of the body.

Stage II. One of the following applies:

• The tumor is between 4 cm or less, and the cancer has spread to nearby lymph nodes but not to distant parts of the body.

• The tumor is bigger than 4 cm but confined to the thyroid. Or has grown only into the strap muscles around the thyroid. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

Stage III. The tumor is any size, and a lot of it has spread outside the thyroid to nearby tissues. These include the windpipe (trachea), voice box (larynx), esophagus, and nerves. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

Stage IVA. The tumor is any size. It has growth into nearby large blood vessels or growth toward the spine. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

Stage IVB. The tumor is any size. It may have growth into the strap muscles or spread into nearby large blood vessels or growth toward the spine. It may or may not have spread to nearby lymph nodes. It has spread to distant sites, such as bones or other organs.

What are the stages of medullary thyroid cancers?

Age is not a part of staging for medullary thyroid cancer.

Stage I. The tumor is 2 cm or less across and is still in the thyroid. It has not spread to nearby lymph nodes or to distant parts of the body.

Stage II.  You have one of the following:

• The tumor is bigger than 2 cm and no larger than 4 cm across. It has not spread outside the thyroid or to nearby lymph nodes or to distant parts of the body.

• The tumor is any size and has started to spread just outside the thyroid into the strap muscles. Or the tumor is bigger than 4 cm but still just in the thyroid. It has not spread to nearby lymph nodes or to distant sites. 

Stage III. The tumor is any size. It may or may not have started to spread just outside the thyroid into the strap muscles. It has spread to lymph nodes around the thyroid in the neck or upper mediastinal, but not to distant sites.

Stage IVA. One of the following applies:

• The tumor is any size and has grown beyond the thyroid gland into nearby structures of the neck. These include the windpipe (trachea), voice box (larnyx), esophagus, and nerves. It may or may not have spread to the lymph nodes. It has not spread to distant sites.

• The tumor is any size and may have grown outside the thyroid into the strap muscles. It has spread to lymph nodes in the neck, upper chest, or behind the throat. It has not spread to distant sites.

Stage IVB. The tumor is any size and the cancer has spread to nearby blood vessels or to tissue near your spine. It may or may not have spread to the lymph nodes. It has not spread to distant sites.

Stage IVC. If the cancer has spread to distant sites, such as the lung, bone or brain, you have stage IVC. The tumor may be any size. It may or may not have spread outside the thyroid into the strap muscles or nearby tissues, blood vessels, or toward your spine. It may or may not have spread to nearby lymph nodes.

What are the stages of anaplastic thyroid cancers?

Age is not a part of staging, and anaplastic thyroid cancer is always stage IV.

Stage IVA. The tumor is any size, but is still in the thyroid gland. It has not spread to nearby lymph nodes or to distant sites of the body.

Stage IVB. One of the following applies:

• The tumor is any size, but is still in the thyroid gland. Cancer has spread to nearby lymph nodes. It has not spread to distant sites.

• The tumor is any size and has grown into the strap muscles around the thyroid. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

• The tumor is any size, and a lot has spread outside the thyroid beyond the strap muscles to nearby tissues. These include the windpipe, voice box, esophagus, nerves, and nearby large blood vessels. It may also have spread toward the spine. It may or may not have spread to nearby lymph nodes. It has not spread to distant sites.

Stage IVC. The cancer has spread to distant sites, such as the liver, lung, or brain. The tumor may be any size. It may or may not have spread outside the thyroid into the strap muscles or nearby tissues. blood vessels, or toward your spine. It may or may not have spread to nearby lymph nodes.

Talking with your healthcare provider

Once your cancer is staged, your healthcare provider will talk with you about what the stage means for your treatment. Make sure to ask any questions or talk about your concerns. While waiting for your results, consider talking with your family or loved ones and writing down your questions so you won't forget to ask about your concerns.