The stages of thyroid cancer are used to describe how far the cancer has spread or how advanced the cancer is in your body. The higher the stage number, the more widespread the cancer is. These stages are important when choosing the best treatments for you.
One way to describe the stages of thyroid cancer is to use the TNM system. This system uses three different codes to describe the size and location of the tumor, whether it has spread to the lymph nodes around the tumor, and whether it can be found in other parts of the body.
In the TNM system, “T” plus a letter or number (0 to 4) is used to describe the size and location of the tumor. The tumor stages for thyroid cancer are:
TX - The primary, or original, tumor cannot be evaluated because of incomplete information.
T0 - There is no evidence of a primary tumor.
T1 - The tumor is 2 centimeters (about three-fourths of an inch) or smaller.
T2 - The tumor is between 2 centimeters and 4 centimeters (about 1½ inches).
T3 - The tumor is larger than 4 centimeters or has begun to grow into nearby tissues outside the thyroid.
T4 - The tumor is any size and has spread beyond the thyroid.
T4a - The tumor is any size and has grown extensively beyond the thyroid gland into nearby tissues of the neck.
T4b - The tumor has grown back toward the spine or into nearby large blood vessels.
The "N" in the TNM system stands for node. Lymph nodes are tiny organs shaped like beans that can be found throughout the body. Lymph nodes help the body fight infections. Regional lymph nodes are near the thyroid, while distant lymph nodes are in other parts of the body. Lymph node stages are:
NX - The regional lymph nodes cannot be evaluated because of incomplete information.
N0 - The cancer has not spread into the regional lymph nodes.
N1 - The cancer has spread to lymph nodes.
N1a - The cancer has spread to lymph nodes in the neck on the same side as the tumor (ipsilateral cervical lymph nodes).
N1b - The tumor has spread to lymph nodes on both sides of the neck, the opposite side of the neck from the tumor, the middle of the neck, or the upper chest.
The "M" in the TNM system is used for cancer that has spread, or metastasized, to other parts of the body. The stages for metastatic thyroid cancer are:
MX - Distant metastasis cannot be evaluated because of incomplete information.
M0 - The cancer has not metastasized, or spread, to other parts of the body.
M1 - The cancer has spread to other parts of the body beyond the thyroid, such as distant lymph nodes (not near the thyroid), internal organs, or bones.
Cancer Stages 0 to IV
After the T, N, and M categories of your cancer have been identified, your doctor will combine this information to assign a stage (I to IV) to your cancer. The higher the number, the more serious (advanced) the cancer is.
The stages of thyroid cancer depend on the kind of cancer you have and your age.
For patients with differentiated thyroid cancers (papillary or follicular thyroid carcinoma) who are younger than 45 years:
-
Stage I: The cancer is any size and may or may not have spread within the neck or upper chest and/or to lymph nodes. However, it has not spread to other parts of the body (any T, any N, M0).
-
Stage II: The cancer is any size and may or may not have spread to lymph nodes. However, it has spread to distant parts of the body, such as the lungs or bones (any T, any N, M1).
For patients with differentiated thyroid cancers (papillary or follicular thyroid carcinoma) who are older than 45 years:
-
Stage I: The cancer is less than 2 centimeters (about three-fourths inch) and is located only in the thyroid gland (T1, N0, M0).
-
Stage II: The cancer is 2 to 4 centimeters (between three-fourths and 1½ inches) and is located only in the thyroid gland (T2, N0, M0).
-
Stage III: The cancer is either larger than 4 centimeters and has not spread beyond the thyroid, or it is any size and has spread just outside the thyroid and/or to the lymph nodes in the neck (T1-T3, N0-N1a, M0).
-
Stage IV - The cancer has spread to lymph nodes or other parts of the body.
- Stage IVA: The cancer is any size and has spread within the neck and/or to lymph nodes in the neck or upper chest (T1-4a, N0-N1b, M0).
- Stage IVB: The cancer is any size and has spread to neck tissues near the backbone or around blood vessels in the neck or upper chest. The cancer may also have spread to the lymph nodes. (T4b, any N, M0).
- Stage IVC: The cancer is any size and has spread to other parts of the body, such as the lung or bone. It may also have spread to nearby lymph nodes (any T, any N, M1).
For patients of any age with medullary thyroid carcinoma:
-
Stage 0 (carcinoma in situ) - No cancer is found in the thyroid but the cancer is detected by screening tests (T0, N0, M0).
-
Stage I: The cancer is less than 2 centimeters (about three-fourths inch) and is located only in the thyroid gland (T1, N0, M0).
-
Stage II: The cancer is less than 2 centimeters (about three-fourths inch) and is located only in the thyroid gland (T1, N0, M0 or T3, NO, MO).
-
Stage III: The cancer is larger than 4 centimeters (about 1½ inches), or it is any size and has spread to the lymph nodes but not to any other parts of the body (T1-T3, N1a, M0).
-
Stage IV - The cancer has spread to lymph nodes or other parts of the body.
- Stage IVA: The cancer is any size and has spread within the neck and/or to lymph nodes in the neck or upper chest (T1-4a, N0-N1b, M0).
- Stage IVB: The cancer is any size and has spread to neck tissues near the backbone or around blood vessels in the neck or upper chest. The cancer may also have spread to the lymph nodes. (T4b, any N, M0).
- Stage IVC: The cancer is any size and has spread to other parts of the body, such as the lung or bone. It may also have spread to nearby lymph nodes (any T, any N, M1).
For patients of any age with undifferentiated (anaplastic) thyroid cancer:
-
Stage IVA: The cancer is any size and has grown beyond the thyroid gland into nearby tissues of the neck. It may or may not have spread to local neck lymph nodes, but it has not traveled to distant sites (T4a, any N, M0).
-
Stage IVB: The cancer is any size and has grown back to the spine or into nearby large blood vessels and it may or may not have spread to lymph nodes. However, it has not spread to distant sites (T4b, any N, M0).
-
Stage IVC: The cancer is any size and may or may not have spread to lymph nodes. However, it has spread to distant sites (any T, any N, M1).
For patients of any age with any kind of thyroid cancer:
-
Recurrent thyroid cancer - The cancer has come back (recurred) after it was treated. Thyroid cancer usually returns in the neck, but it can reappear in another part of the body (such as the lymph nodes, lungs, or bones). Doctors may assign a new stage to the recurrent cancer based on how far it has spread, but this usually involves a less formal process than the original staging.
This content has been reviewed and approved by Myo Thant, MD.