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The stages of thyroid cancer

Men and woman discussing thyroid cancer

This page tells you about the stages of thyroid cancer. You can find the following information

 

A quick guide to what's on this page

The stages of thyroid cancer

The stage of a cancer tells the doctor how big the cancer is and whether it has spread. It is important because treatment is often decided according to the stage of a cancer. There are different ways of staging cancers. In thyroid cancer, doctors use the TNM system and the number system.

TNM stages of thyroid cancer

TNM stands for tumour, node, metastasis. This system describes the size of a primary tumour (T), whether there are lymph nodes with cancer cells in them (N), and whether the cancer has spread to a different part of the body (M).

  • T stages – there are 4 main T stages for thyroid cancers (except anaplastic thyroid cancer). T1 is the smallest size and T4 is the largest
  • N stages – there are 2 main N groups. Either the cancer has not spread to the lymph nodes (N0) or it has spread into the nodes (N1)
  • M stages – there are 2 possible M stages. Either the cancer has not spread to other body parts (M0) or it has spread (M1)

The number stages of thyroid cancer

The TNM information can be grouped into number stages. For papillary, follicular and medullary cancers they are numbered from 1 to 4. For papillary and follicular cancer the stages take into account the patient's age. Stage 1 is the earliest stage and stage 4 is the most advanced. All anaplastic thyroid cancers are considered stage 4 at diagnosis.
 

CR PDF Icon You can view and print the quick guides for all the pages in the treating thyroid cancer section.

 

 

Why staging is important

The stage of a cancer means how big it is and whether it has spread. The tests and scans you have when diagnosing your cancer give some information about the stage. It is important because treatment is often decided according to the stage of a cancer. It is often not possible to fully stage your cancer until after your surgery. 

There are different ways of staging cancers. The 2 main ways are the TNM system and number system. There is more about staging cancers in the about cancer section.

 

The TNM stages of thyroid cancer

TNM stands for Tumour, Node, and Metastasis. The system describes the size of a primary tumour (T), whether there are lymph nodes with cancer cells in them (N), and whether the cancer has spread to a different part of the body (M).

Tumour (T)

There are 4 main T stages for thyroid cancers, except anaplastic thyroid cancer.

  • T1a – the tumour is entirely inside the thyroid and is less than 1cm across in any direction

    Diagram showing stage T1a thyroid cancer
  • T1b – the tumour is entirely inside the thyroid and is more than 1 cm but no more than 2cm across in any direction

    Diagram showing stage T1b thyroid cancer
  • T2 – the tumour is entirely inside the thyroid and is more than 2cm but no more than 4cm across in any direction

    Diagram showing stage T2 thyroid cancer
  • T3 – the tumour is more than 4cm across or it has begun to grow into tissues close to the thyroid

    Diagram showing stage T3 thyroid cancer
  • T4a – the cancer has grown outside the covering of the thyroid gland into nearby soft tissue, such as the voice box (larynx), windpipe (trachea), food pipe (oesophagus) or the voice box nerve (recurrent laryngeal nerve). T4a thyroid cancer is called moderately advanced thyroid cancer.

    Diagram showing stage T4a thyroid cancer
  • T4b – the cancer has grown outside the thyroid gland into the area surrounding the bones of the spine, or one of the main blood vessels in the neck area. T4b thyroid cancer is called very advanced thyroid cancer.


    Diagram showing stage T4b thyroid cancer

All anaplastic thyroid cancers are considered to be T4 tumours at the time of diagnosis.

  • T4a means that the tumour is still within the thyroid gland
  • T4b means that the tumour has spread outside the thyroid

Node (N)

There are 2 possible stages of lymph node involvement. N0 means that the cancer has not spread to nearby lymph nodes. N1 means the cancer has spread to nearby lymph nodes and is divided into 2 groups

  • N1a means the cancer has spread to lymph nodes close to the thyroid in the neck (called pretracheal, paratracheal, and prelaryngeal lymph nodes)

    Diagram showing stage N1a thyroid cancer
  • N1b means the cancer has spread to other lymph nodes in the neck (called cervical nodes) or to lymph nodes behind the throat (retropharyngeal) or in the upper chest (the superior mediastinal nodes)


    Diagram showing N1b thyroid cancer

Metastases (M)

There are 2 possible stages of cancer spread. Either the cancer has not spread to another part of the body (M0) or it has spread (M1).

Diagram showing stage M1 thyroid cancer

 

 

The number stages of thyroid cancers

The number staging depends on the type of thyroid cancer you have. There are different systems for

Papillary and follicular thyroid cancer

The number stages for papillary and follicular thyroid cancer are the same. These types are classed as differentiated thyroid cancers. There are 4 number stages. These cancers are staged differently depending on your age. These types of thyroid cancer tend to respond well to treatment, particularly if you are younger.

If you are under 45

Stage 1 means you have thyroid cancer which may or may not have spread to nearby lymph nodes. The tumour can be any size but has not spread to distant areas of the body. In TNM staging, this is the same as Any T, Any N, M0.

Stage 2 means your cancer has spread to other parts of the body (Any T, Any N, M1).

If you are over 45

Stage 1 means your cancer is only inside the thyroid and is less than 2cm across (T1, N0, M0).

Stage 2 means your cancer is between 2cm and 4cm across, and is only inside the thyroid (T2, N0, M0).

Stage 3 means the tumour is

  • larger than 4 cm or has grown slightly outside the thyroid, but it has not spread to nearby lymph nodes or other parts of the body (T3, N0, M0)
  • any size within the thyroid gland or has started to grow slightly outside the thyroid. It has spread to lymph nodes close to the thyroid in the neck but not to other parts of the body (T1-T3, N1a, M0)

Stage 4 is divided into 3 groups from A to C

Stage 4A means the tumour

  • has grown beyond the thyroid gland and into nearby tissues in the neck. It may or may not have spread to nearby lymph nodes but has not spread to other parts of the body (T4a, N0 or N1a, M0) OR
  • is any size and may have grown into nearby tissues in the neck. It has spread to certain lymph nodes in the neck (cervical nodes) or to lymph nodes in the upper chest (the superior mediastinal nodes) or behind the throat (retropharyngeal nodes) but not to other parts of the body (T1-T4a, N1b, M0)

Stage 4B means the tumour has grown into the area surrounding the bones of the spine or into nearby large blood vessels. It may or may not have spread to nearby lymph nodes, but it has not spread to other parts of the body (T4b, Any N, M0).

Stage 4C means the cancer has spread to other parts of the body (Any T, Any N, M1).

Medullary thyroid cancer

There are 4 number stages for people of any age with medullary thyroid cancer.

Stage 1 means that the tumour is 2 cm or less across and has not grown outside the thyroid. It has not spread to nearby lymph nodes or other parts of the body. In TNM staging, this is the same as T1, N0, M0.

Stage 2 means the tumour is

  • between 2 cm and 4cm across and has not grown outside the thyroid at all (T2, N0, M0) OR
  • larger than 4 cm or has grown slightly outside the thyroid, but has not spread to nearby lymph nodes or other parts of the body (T3, N0, M0)

Stage 3 means that the tumour is any size within the thyroid gland or has started to grow slightly outside the thyroid. It has spread to lymph nodes close to the thyroid in the neck but not to other parts of the body (T1-T3, N1a, M0).

Stage 4 is divided into 3 groups from A to C

Stage 4A means the tumour 

  • has grown beyond the thyroid gland and into nearby tissues of the neck. It may or may not have spread to nearby lymph nodes but has not spread to other parts of the body (T4a, N0 or N1a, M0) OR 
  • is any size and may have grown into nearby tissues in the neck. It has spread to the cervical lymph nodes in the neck or to nodes in the upper chest (the superior mediastinal nodes) or behind the throat (retropharyngeal nodes), but not to other parts of the body (T1 to T4a, N1b, M0)

Stage 4B means the tumour has grown into the area surrounding the bones of the spine or into nearby large blood vessels. It may or may not have spread to nearby lymph nodes, but it has not spread to other parts of the body (T4b, Any N, M0).

Stage 4C means the cancer has spread to other parts of the body.

Anaplastic (undifferentiated) thyroid cancer

All anaplastic thyroid cancers are considered to be stage 4 when they are diagnosed. This stage is divided into 3 groups from A to C.

Stage 4A means the tumour is still within the thyroid gland. It may or may not have spread to nearby lymph nodes, but has not spread to other parts of the body (T4a, Any N, M0).

Stage 4B means the tumour has grown outside the thyroid gland. It may or may not have spread to nearby lymph nodes, but has not spread to other parts of the body (T4b, Any N, M0).

Stage 4C means the cancer has spread to other parts of the body (Any T, Any N, M1).

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Updated: 5 November 2014