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Thyroid Cancer Stages

The most common staging method for thyroid cancer is the AJCC (American Joint Committee on Cancer) TNM system. Using this system, thyroid cancer staging depends on the type of thyroid cancer, the extent of the tumor (size and growth into nearby structures), spread to nearby lymph nodes, and spread to distant organs. This form of staging is referred to as TNM, where: T refers to Tumor, N refers to Nodes (lymph nodes), and M refers to Metastasis. Based on the characteristics of each letter, a stage between I – IV is assigned.

Differentiated Thyroid Cancer (Papillary or Follicular)

AJCC Stage Age at diagnosis Stage grouping Differentiated Thyroid Cancer Stage description*

 

I

 

Younger than 55 years

Any T

Any N

M0

 

The cancer is any size (Any T) and might or might not have spread to nearby lymph nodes (Any N).

It has not spread to distant sites (M0).

OR
55 years or older

T1

N0 or NX

M0

The cancer is no larger than 2 cm across and confined to the thyroid (T1).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

OR
55 years or older

T2

N0 or NX

M0

The cancer is larger than 2 cm across but no larger than 4 cm and confined to the thyroid (T2).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

 

II

Younger than 55 years

Any T

Any N

M1

The cancer can be any size (Any T). It might or might not have spread to nearby lymph nodes (Any N).

It has spread to other parts of the body, such as distant lymph nodes, internal organs, bones, etc. (M1).

OR
55 years or older

T1

N1

M0

The cancer is no larger than 2 cm across and confined to the thyroid (T1).

It has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0).

OR
55 years or older

T2

N1

M0

The cancer is larger than 2 cm across but no larger than 4 cm and confined to the thyroid (T2).

It has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0).

OR
55 years or older

T3a or T3b

Any N

M0

The cancer is larger than 4 cm but confined to the thyroid (T3a) or it has grown into the strap muscles around the thyroid (T3b).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

III 55 years or older

T4a

Any N

M0

The cancer 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 (T4a).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

IVA 55 years or older

T4b

Any N

M0

The cancer is any size and has grown extensively beyond the thyroid gland back toward the spine or into nearby large blood vessels (T4b).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

IVB 55 years or older

Any T

Any N

M1

The cancer is any size (Any T) and might or might not have spread to nearby lymph nodes (Any N).

It has spread to other parts of the body, such as distant lymph nodes, internal organs, bones, etc. (M1).

TX: Main tumor cannot be assessed due to lack of information.

T0: No evidence of a primary tumor.

NX: Regional lymph nodes cannot be assessed due to lack of information.

Anaplastic (undifferentiated) Thyroid Cancer

All anaplastic thyroid cancers are considered stage IV

AJCC Stage Stage grouping Anaplastic Thyroid Cancer Stage description*

 

IVA

 

T1, T2 or T3a

N0 or NX

M0

The cancer is any size but confined to the thyroid (T1, T2, or T3a).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

IVB

T1, T2 or T3a

N1

M0

The cancer is any size but confined to the thyroid (T1, T2, or T3a). It has spread to nearby lymph nodes (N1).

It has not spread to distant sites (M0).

OR

T3b

Any N

M0

The cancer is any size and has grown into the strap muscles around the thyroid (T3b).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

OR

T4

Any N

M0

The cancer 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 or back toward the spine or into nearby large blood vessels (T4).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

IVC

Any T

Any N

M1

The cancer is any size (Any T) and might or might not have spread to nearby lymph nodes (Any N).

It has spread to other parts of the body, such as distant lymph nodes, internal organs, bones, etc. (M1).

TX: Main tumor cannot be assessed due to lack of information.

T0: No evidence of a primary tumor.

NX: Regional lymph nodes cannot be assessed due to lack of information.

Medullary Thyroid Cancer

Age is not a factor in the stage of medullary thyroid cancer.

AJCC Stage Stage grouping Medullary Thyroid Cancer Stage description*

I

T1

N0

M0

The cancer is 2cm or smaller and confined to the thyroid (T1).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

II

T2

N0

M0

The cancer is larger than 2cm but no more than 4cm across and confined to the thyroid (T2).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

OR

T3

N0

M0

The cancer is larger than 4cm and confined the thyroid or any size and growing outside of the thyroid but not involving nearby structures (T3).

It has not spread to nearby lymph nodes (N0) or to distant sites (M0).

III

T1, T2, or T3

N1a

M0

The cancer is any size and might be growing outside of the thyroid but not involving nearby structures (T1, T2, T3).

It has spread to lymph nodes in the neck (pretracheal, paratracheal, prelaryngeal, or upper mediastinal) (N1a) but not to other lymph nodes or to distant sites (M0).

IVA

T4a

Any N

M0

The cancer is any size and has grown 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 (T4a).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

OR

T1, T2, or T3

N1b

M0

The cancer is any size and might be growing outside of the thyroid but not involving nearby structures (T1, T2, T3).

It has spread to certain lymph nodes in the neck such as cervical or jugular nodes (N1b). It has not spread to distant sites (M0).

IVB

T4b

Any N

M0

The cancer is any size and has grown either back toward the spine or into nearby large blood vessels (T4b).

It might or might not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).

IVC

Any T

Any N

M1

The cancer is any size and might have grown into nearby structures (Any T).

It might or might not have spread to nearby lymph nodes (Any N). It has spread to distant sites such as the liver, lung, bone or brain (M1).

TX: Main tumor cannot be assessed due to lack of information.

T0: No evidence of a primary tumor.

NX: Regional lymph nodes cannot be assessed due to lack of information.

References:

American Joint Committee on Cancer. Thyroid – Differentiated and Anaplastic. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017: 873.

American Joint Committee on Cancer. Thyroid – Medullary. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017: 891.