Staging helps determine the extent of cancer. It helps in predicting the chance for cure and is one of the main determinants of the treatment options. It is based on the results of the physical exam, imaging and biopsy results. The most common staging system is the TNM staging described by the American Joint Committee on Cancer (AJCC). The current staging for well differentiated thyroid cancer (papillary and follicular) is divided by age as younger patients have lower likelihood of dying from these types of thyroid cancer.
T describes the size of the tumor and growth into the surrounding structures
N describes the extent of lymph node involvement
M describes if the cancer has spread to other organs in the body.
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Papillary and Follicular Thyroid Cancer |
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Stage |
TNM |
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I |
Any T, any N, M0 |
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II |
Any T, any N, M1 |
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≥45 years old |
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I |
T1, N0, M0 |
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II |
T2, N0, M0 |
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III |
T3, N0, M0; T1-3, N1a, M0 |
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IVA |
T4a, N0-1a, M0; T1-4a, N1b, M0 |
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IVB |
T4b, any N, M0 |
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IVC |
Any T, any N, M1 |
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Medullary Thyroid Cancer |
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I |
T1, N0, M0 |
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II |
T2-3, N0, M0 |
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III |
T1-3, N1a, M0 |
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IVA |
T4a, N0-1a, M0; T1-4a, N1b, M0 |
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IVB |
T4b, any N, M0 |
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IVC |
Any T, any N, M1 |
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Anaplastic Thyroid Cancer |
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IVA |
T4a, Any N, M0 |
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IVB |
T4b, any N, M0 |
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IVC |
Any T, any N, M1 |
T Staging for thyroid cancer (other than anaplastic thyroid cancer)
TX: Primary tumor cannot be assessed.
T0: No evidence of primary tumor.
T1: The tumor is 2 cm (slightly less than an inch) across or smaller and has not grown out of the thyroid.
- T1a: The tumor is 1 cm across or smaller and has not grown outside the thyroid.
- T1b: The tumor is larger than 1 cm but not larger than 2 cm across and has not grown outside of the thyroid.
T2: The tumor is more than 2 cm but not larger than 4 cm across and has not grown out of the thyroid.
T3: The tumor is larger than 4 cm across, or it grown into nearby tissues outside the thyroid.
T4a: The tumor is any size and has grown extensively beyond the thyroid gland into nearby tissues of the neck, such as the larynx (voice box), trachea (windpipe), esophagus (tube connecting the throat to the stomach), or the nerve to the larynx. This is also called moderately advanced disease.
T4b: The tumor is any size and has grown either back toward the spine or into nearby large blood vessels. This is also called very advanced disease.
T categories for anaplastic thyroid cancer
All anaplastic thyroid cancers are considered T4 tumors at the time of diagnosis.
T4a: The tumor is still within the thyroid.
T4b: The tumor has grown outside the thyroid.
N categories for thyroid cancer
NX: Regional (nearby) lymph nodes cannot be assessed.
N0: The cancer has not spread to nearby lymph nodes.
N1: The cancer has spread to nearby lymph nodes.
- N1a: The cancer has spread to lymph nodes around the thyroid in the neck (called pretracheal, paratracheal, and prelaryngeal lymph nodes).
- N1b: The cancer has spread to other lymph nodes in the neck (called cervical) or to lymph nodes behind the throat (retropharyngeal) or in the upper chest (superior mediastinal).
M categories for thyroid cancer
MX: Distant metastasis cannot be assessed.
M0: There is no distant metastasis.
M1: The cancer has spread to other parts of the body, such as internal organs, bones, etc.