Oncologist-approved cancer information from the American Society of Clinical Oncology
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Thyroid Cancer

This section has been reviewed and approved by the Cancer.Net Editorial Board, 7/2013
Stages

ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread. This is called the stage. To see other pages in this guide, use the colored boxes on the right side of your screen, or click “Next” at the bottom.

Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body. Doctors use diagnostic tests to determine the cancer’s stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancer.

One tool that doctors use to describe the stage is the TNM system. TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:

  • How large is the primary tumor and where is it located? (Tumor, T)
  • Has the tumor spread to the lymph nodes? (Node, N)
  • Has the cancer metastasized to other parts of the body? (Metastasis, M)

The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.

In addition to the TNM system, papillary and follicular thyroid cancers are also staged by the age of the patient.

Here are more details on each part of the TNM system for thyroid cancer:

Tumor. Using the TNM system, the letter “T” plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. When describing “T” in thyroid cancer, doctors may subdivide the general categories by adding the letter “s” to indicate a solitary (single) tumor or “m” to indicate multifocal (more than one) tumors. Specific tumor stage information is listed below.

TX: The primary tumor cannot be evaluated.

T0: There is no evidence of a tumor.

T1: The tumor is 2 centimeters (cm) or smaller and limited to the thyroid.

T1a: The tumor is 1 cm or smaller.

T1b: The tumor is bigger than 1 cm but less than 2 cm.

T2: The tumor is at least 2 cm, but it is not larger than 4 cm and is limited to the thyroid.

T3: The tumor is larger than 4 cm, but the tumor does not extend beyond the thyroid gland.

T4: The tumor is any size and has extended beyond the thyroid.

T4a: The tumor has spread beyond the thyroid to nearby soft tissues, the larynx, trachea, esophagus or recurrent laryngeal nerve.

T4b: The tumor has spread beyond the regions stated in T4a (above).

Node. The “N” in the TNM staging system stands for lymph nodes. There are many regional lymph nodes located in the head and neck area, and careful assessment of lymph nodes is an important part of staging thyroid cancer. Lymph nodes in other parts of the body are called distant lymph nodes.

NX: The regional lymph nodes cannot be evaluated.

N0: There is no evidence of cancer in the regional lymph nodes.

N1: Cancer has spread to the lymph nodes.

N1a: Cancer has spread to the lymph nodes around the thyroid (called the central compartment; pretracheal, paratracheal, and prelaryngeal lymph nodes.)

N1b: Cancer has spread beyond the central compartment, including unilateral cervical (lymph nodes on one side of the neck), bilateral cervical (lymph nodes on both sides of the neck), contralateral cervical (the opposite side of the tumor), or mediastinal (the chest) lymph nodes.

Distant metastasis. The “M” in the TNM system indicates whether cancer has spread to other parts of the body.

MX: Distant metastasis cannot be evaluated.

M0: Cancer has not spread to other parts of the body.

M1: Cancer has spread to other parts of the body.

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications. For thyroid cancer, this staging system differs by tumor type. For papillary or follicular thyroid cancers, it also depends on the age of the patient.

Papillary or follicular thyroid tumors, in a person younger than 45

Stage I: This stage describes a tumor (any T) with or without spread to lymph nodes (any N) and no distant metastasis (M0).

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Stage I Thyroid Cancer

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Stage II: This stage describes a tumor (any T) with any metastasis (M1) regardless of whether it has spread to the lymph nodes (any N).

Stage II Thyroid Cancer

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Papillary or follicular thyroid tumors, in a person 45 and older

Stage I: This stage describes any small tumor (T1) with no spread to lymph nodes (N0) and no metastasis (M0).

Stage I Thyroid Cancer

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Stage II: This stage describes a larger, noninvasive tumor (T2) with no spread to lymph nodes (N0) and no metastasis (M0).

Stage II Thyroid Cancer

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Stage III: This stage describes a tumor larger than 4 cm but contained in the thyroid (T3) with no spread to lymph nodes (N0) and no metastasis (M0). Or, any localized tumor (T1-3) with spread to the central compartment of lymph nodes (N1a), but no distant spread (M0).

Stage III Thyroid Cancer

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Stage IVA: This stage describes a tumor that has spread to nearby structures (T4a), regardless of whether it has spread to the lymph nodes (any N), but it has not spread to distant places (M0). Or, this describes a localized tumor (T1-3), with lymph node spread beyond the central compartment (N1b), but no distant spread (M0).

Stage IVB: This stage describes a tumor that has spread beyond nearby structures (T4b), regardless of spread to lymph nodes (any N), but no distant spread (M0).

Stage IVC: This stage describes all tumors (any T, any N) when there is evidence of metastasis (M1).

Stage IV Thyroid Cancer

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Medullary thyroid tumors

Stage I: This stage describes a small tumor (T1) with no spread to lymph nodes (N0) and no distant metastasis (M0).

Medullary Stage I Thyroid Cancer

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Stage II: This stage describes a larger localized tumor (T2, T3) with no spread to lymph nodes (N0) and no metastasis (M0).

Medullary Stage II Thyroid Cancer

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Stage III: This stage describes any localized tumor (T1-3) that has spread to the central compartment of lymph nodes (N1a) but has not metastasized (M0).

Medullary Stage III Thyroid Cancer

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Stage IVA: This stage describes a tumor that has spread to nearby structures (T4a), regardless of whether it has spread to the lymph nodes (any N), but it has not spread to distant places (M0). Or, this describes a localized tumor (T1-3), with lymph node spread beyond the central compartment (N1b), but no distant spread (M0).

Stage IVB: This stage describes a tumor that has spread beyond nearby structures (T4b), regardless of spread to lymph nodes (any N), but no distant spread (M0).

Stage IVC: This stage is used when there is evidence of metastasis (any T, any N, M1).

Medullary Stage IV Thyroid Cancer

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Anaplastic thyroid tumors

Stage IV: All anaplastic thyroid tumors are classified as stage IV, regardless of tumor size, location, or metastasis.

Stage IVA: This stage describes an anaplastic tumor that has spread to nearby structures (T4a), regardless of whether it has spread to the lymph nodes (any N), but it has not spread to distant places (M0).

Stage IVB: This stage describes an anaplastic tumor that has spread beyond nearby structures (T4b), regardless of spread to lymph nodes (any N), but no distant spread (M0).

Stage IVC: This stage is used when there is evidence of metastasis (any T, any N, M1).

Recurrent: Recurrent cancer is cancer that has come back after treatment. If there is a recurrence, the cancer may need to be staged again (called re-staging) using the system above.

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Seventh Edition (2010), published by Springer-Verlag New York, www.cancerstaging.net.

Information about the cancer’s stage will help the doctor recommend a treatment plan for you. Choose “Next” (below, right) to continue reading about treatment options for this type of cancer. Or, use the colored boxes located on the right side of your screen to visit any section.

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