Staging

The stage of a cancer describes its size and if it has spread from where it started. This information affects the decisions you and your doctor make about your treatment.

There are two ways of staging thyroid cancer.

The first is TNM staging:

  • T describes the size of the cancer.
  • N describes whether the cancer has spread to the lymph nodes.
  • M describes if the cancer has spread to other parts of the body.

The second is number staging. Information from the TNM system can also be used to give a numbered stage, showing how far the cancer may have spread on a scale of 1 to 4. All people under 45 with papillary or follicular thyroid cancer have either stage 1 or stage 2 cancer. People over 45 may have up to stage 4 cancer.

The staging of thyroid cancer is complicated. Your doctor or nurse can explain it to you in more detail and answer any questions you may have.

Staging thyroid cancer

The stage of a cancer describes its size and whether it has spread beyond the area of the body where it started. Staging systems are often updated to help doctors plan the best treatment and give an idea of what is likely to happen. This means they are becoming more detailed and complicated. 

Different types of cancer are staged differently. The stages we describe here are about thyroid cancer. The most common staging system is the TNM system. 

TNM staging

T describes the size of the tumour and whether it has spread into nearby tissues around the thyroid gland. 

N describes whether the cancer has spread to the lymph nodes close to the thyroid gland. 

M describes whether the cancer has spread to other parts of the body, such as the lungs or the bones (metastatic or secondary cancer).


TNM staging

T – Tumour

Doctors put a number next to the T to describe the size and spread of the cancer. 

T1 means the tumour has not grown outside the thyroid gland. 

  • T1a means the tumour is 1cm or smaller.
  • T1b means the tumour is between 1cm and 2cm.

T2 means the tumour is between 2cm and 4cm. It has not grown outside the thyroid gland.

T3 means the tumour is bigger than 4cm or it has grown slightly outside the thyroid gland.

T4 means the tumour has grown outside the thyroid gland and is attached to nearby structures.

  • T4a means the tumour has started to grow into nearby structures, such as the voicebox (larynx), windpipe (trachea) or gullet (oesophagus).
  • T4b means the tumour has grown into the area close to the spine or into a major blood vessel in the neck.

N – Nodes

The N may have a number written next to it, which gives information about the nodes that were examined.

N0 means the lymph nodes are not affected.

N1 means the cancer has spread to lymph nodes close to the thyroid gland or in the neck or chest area.

  • N1a means the cancer has spread to lymph nodes in the middle of the neck, close to the thyroid gland.
  • N1b means the cancer has spread to lymph nodes in the side of the neck or top of the chest.

M – Metastases

The M may have a number written next to it, which gives information about whether the cancer has spread.

M0 means the cancer has not spread within the body.

M1 means the cancer has spread to another part of the body.


Number stages

Doctors often combine the information from the TNM system into an overall number stage, from 1 to 4.

Unlike most cancers, papillary and follicular thyroid cancer are also staged according to the age of the person.

Papillary or follicular thyroid cancer in people aged under 45

Stage 1

The tumour can be any size and the cancer may or may not have spread to nearby lymph nodes. It has not spread to other parts of the body.

Stage 2

The tumour is any size and the cancer may or may not have spread to nearby lymph nodes. It has spread to other parts of the body, such as the bones or lungs. 

There is no stage 3 or 4 thyroid cancer for people in this age group.

Papillary or follicular thyroid cancer in people aged 45 and over

Stage 1

The tumour is no bigger than 2cm and hasn’t grown outside the thyroid gland. The cancer has not spread to the lymph nodes or to other parts of the body.

Stage 2

The tumour is between 2–4 cm. It has not grown outside the thyroid gland. The cancer has not spread to the lymph nodes or other parts of the body.

Stage 3

The tumour is bigger than 4cm and has not grown outside the thyroid gland. The cancer has not spread to the lymph nodes or other parts of the body.

Or the tumour is any size and has spread just outside the thyroid gland. It is not affecting nearby structures. The cancer has spread to nearby lymph nodes in the middle of the neck, close to the thyroid gland. It has not spread to lymph nodes in the side of the neck or other parts of the body.

Stage 4A

The tumour is any size and the cancer has spread into surrounding structures in the neck, such as the muscles, nerves or blood vessels. It may or may not have spread to the lymph nodes, but it has not spread to other parts of the body.

Or the tumour is any size and the cancer may have spread just outside the thyroid gland. It has spread to lymph nodes in the side of the neck away from the thyroid gland, or in the top of the chest. It has not spread to other parts of the body.

 

Stage 4B

The tumour is any size and the cancer has spread to other parts of the neck. It may or may not have spread to the lymph nodes, but it has not spread to other parts of the body.

Stage 4C

The tumour is any size and the cancer may or may not have spread to the lymph nodes. It has spread to other parts of the body, such as the lung or bones. 

The staging of thyroid cancer is complicated. If you would like more information, you can ask your doctor or nurse to explain it in more detail.

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