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Thyroid cancer

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Staging thyroid cancer

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. Extent includes the size of the tumour and how far the cancer has grown outside the thyroid. Your healthcare team uses the stage to plan treatment and estimate your prognosis.

The most common staging system for thyroid cancer is the TNM system. Each stage is given a number from 1 to 4. They are usually given as the Roman numerals I, II, III and IV. Generally, the higher the number, the more the cancer has spread.

When describing the stage, doctors may use the terms local, regional and distant. Local means that the cancer is only in the thyroid and has not spread to other parts of the body. Regional means close to or around the thyroid. Distant means in a part of the body farther from the thyroid.

Differentiated thyroid cancer (papillary and follicular carcinomas), anaplastic carcinoma and medullary carcinoma each have their own staging. Differentiated thyroid cancer is usually classified into risk groups as well.

TNM descriptions

T describes the size of the primary tumour and if it has grown into tissues around the thyroid. T is usually given as a number from 1 to 4. A higher number means that the tumour is larger or has grown farther into nearby tissues.

N describes the lymph nodes around the thyroid. N0 means the cancer hasn’t spread to the lymph nodes. N1 means cancer has spread to lymph nodes. N1 also describes the location of the lymph nodes.

M describes whether or not the cancer has spread, or metastasized, to other parts of the body. M0 means that cancer has not spread to other parts of the body. M1 means that it has spread to other parts of the body.

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Differentiated thyroid cancer

Staging for differentiated thyroid cancer depends on the age of the person at diagnosis.

Younger than 45 years of age

People younger than 45 years of age at diagnosis will have either stage I or stage II differentiated thyroid cancer.

Stage I

TNMDescription

any T

any N

M0

The tumour is any size. It may have grown through the thyroid and spread to nearby tissues and structures.

The cancer may have spread to lymph nodes in the neck or between the lungs.

Stage II

TNMDescription

any T

any N

M1

The tumour is any size. It may have grown through the thyroid and spread to nearby tissues and structures.

The cancer may have spread to lymph nodes in the neck or between the lungs.

The cancer has spread to other parts of the body, such as the lungs or bone (called distant metastasis).

Older than 45 years of age

People older than 45 years of age at diagnosis will be given a stage from I to IV for differentiated thyroid cancer.

Stage I

TNMDescription

T1a or T1b

N0

M0

The tumour is 2 cm or smaller. It is only in the thyroid.

Stage II

TNMDescription

T2

N0

M0

The tumour is larger than 2 cm but not more than 4 cm. It is only in the thyroid.

Stage III

TNMDescription

T3

N0

M0

The tumour is either:

  • larger than 4 cm and only in the thyroid
  • any size and has grown into tissues just outside the thyroid

T1, T2 or T3

N1a

M0

The tumour is any size. It may have grown into tissues just outside the thyroid.

The cancer has spread to lymph nodes in the front of the neck near the trachea (windpipe) and larynx (voice box).

Stage IV

StageTNMDescription

IVA

T1, T2 or T3

N1b

M0

The tumour is any size. It may have grown into tissues just outside the thyroid.

The cancer has spread to lymph nodes in one or both sides of the neck or to lymph nodes between the lungs.

T4a

N0 or N1

M0

The tumour is any size. It has grown through the thyroid and spread to one or more of the following:

  • nearby tissues under the skin
  • the larynx
  • the trachea
  • the esophagus
  • the nerve that goes to the larynx (called the recurrent laryngeal nerve)

The cancer may have spread to lymph nodes in the neck or between the lungs.

IVB

T4b

any N

M0

The tumour is any size. It has grown through the thyroid and spread to one of the following:

  • fibrous tissue in front of the spine
  • blood vessels between the lungs
  • a carotid artery (one of the blood vessels that carry blood to the neck, face and brain).

The cancer may have spread to lymph nodes in the neck or between the lungs.

IVC

any T

any N

M1

The tumour is any size. It may have grown through the thyroid and spread to nearby tissues and structures.

The cancer may have spread to lymph nodes in the neck or between the lungs.

The cancer has spread to other parts of the body, such as the lungs or bone (called distant metastasis).

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Anaplastic carcinoma

All anaplastic carcinomas are stage IV.

StageTNMDescription

IVA

T4a

any N

M0

The tumour is any size. It is only in the thyroid.

The cancer may have spread to lymph nodes in the neck or between the lungs.

IVB

T4b

any N

M0

The tumour is any size. It has grown through the thyroid and spread to nearby tissues and structures.

The cancer may have spread to lymph nodes in the neck or between the lungs.

IVC

any T

any N

M1

The tumour is any size. It may have grown through the thyroid and spread to nearby tissues and structures.

The cancer may have spread to lymph nodes in the neck or between the lungs.

The cancer has spread to other parts of the body, such as the lungs or bone (called distant metastasis).

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Medullary carcinoma

StageTNMDescription

I

T1a or T1b

N0

M0

The tumour is 2 cm or smaller. It is only in the thyroid.

II

T2 or T3

N0

M0

The tumour is either:

larger than 2 cm and only in the thyroid

any size and has grown into tissues just outside the thyroid

III

T1, T2 or T3

N1a

M0

The tumour is any size. It may have grown into tissues just outside the thyroid.

The cancer has spread to lymph nodes in the front of the neck near the trachea and larynx.

IVA

T1, T2 or T3

N1b

M0

The tumour is any size. It may have grown into tissues just outside the thyroid.

The cancer has spread to lymph nodes in one or both sides of the neck or to lymph nodes between the lungs.

T4a

any N

M0

The tumour is any size. It has grown through the thyroid and spread to one or more of the following:

  • nearby tissues under the skin
  • the larynx
  • the trachea
  • the esophagus
  • the nerve that goes to the larynx (called the recurrent laryngeal nerve)

The cancer may have spread to lymph nodes in the neck or between the lungs.

IVB

T4b

any N

M0

The tumour is any size. It has grown through the thyroid and spread to one of the following:

  • fibrous tissue in front of the spine
  • blood vessels between the lungs
  • a carotid artery (one of the blood vessels that carry blood to the neck, face and brain)

The cancer may have spread to lymph nodes in the neck or between the lungs.

IVC

any T

any N

M1

The tumour is any size. It may have grown through the thyroid and spread to nearby tissues and structures.

The cancer may have spread to lymph nodes in the neck or between the lungs.

The cancer has spread to other parts of the body, such as the lungs or bone (called distant metastasis).

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Recurrent thyroid cancer

Recurrent thyroid cancer means that the cancer has come back after it has been treated. If it comes back in the same place where the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. It can also recur in another part of the body, which is called distant metastasis, or distant recurrence.

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