Staging of thyroid cancer

The stage of thyroid cancer describes its size and whether it has spread beyond the area of the body where it started.

What is staging?

The stage of a cancer describes its size and whether it has spread from where it started. Staging helps doctors plan the best treatment for you.

Different types of thyroid cancer are staged differently. This information is about staging the most common types – papillary and follicular thyroid cancer. We also have information about:

We understand that waiting to know the stage of your cancer can be a worrying time. We're here if you need someone to talk to. You can:

TNM staging

The most common staging system is the TNM system.

  • 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).

T – Tumour

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

T1 means the tumour is 2cm or less and 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.

  • T3a means the tumour is bigger than 4cm and has not grown outside the thyroid gland.
  • T3b means the tumour is of any size and has grown slightly outside the thyroid gland into nearby muscles.

T4 means the tumour has grown outside the thyroid gland and into nearby structures.

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

N – Nodes

The N may have a number written next to it. This 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 one or both sides of the neck, or the upper part of the chest.

M – Metastases

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

  • M0 means the cancer has not spread to other parts of the body.
  • M1 means the cancer has spread to another part of the body.

Number stages

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

Unlike most cancers, papillary and follicular thyroid cancer are also staged based on your age.

Papillary or follicular thyroid cancer in people aged under 55

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 55 and over

Stage 1

The tumour is no bigger than 4cm and has not 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 4cm or less, it may have spread to the lymph nodes in the neck or upper chest, but not spread to other parts of the body.

Or the tumour is more than 4cm and not grown outside the thyroid gland. It may or may not have spread to nearby lymph nodes, but it has not spread to other parts of the body.

Or a tumour of any size, that has spread to nearby muscles in the neck. It may or may not have spread to nearby lymph nodes, but it has not spread to the rest of the body.

Stage 3

The tumour is any size and has grown into nearby structures, such as the voicebox, windpipe or gullet. It may or may not have spread to nearby lymph nodes, but it has not spread to other parts of the body.

Stage 4A

The tumour is any size and has grown into:

  • the area close to the spine
  • a main blood vessel in the neck or upper chest.

It may or may not have spread to nearby lymph nodes, but it has not spread to other parts of the body.

Stage 4B

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, bones or liver.

The staging of thyroid cancer is complicated. If you would like more information, ask your doctor or specialist nurse to explain it in more detail. Or you can call the Macmillan Support Line on 0808 808 00 00.

About our information

  • References

    Below is a sample of the sources used in our thyroid cancer information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    British Medical Journal. Best Practice Guidelines, Thyroid cancer. 2020.

    European Society Medical Oncology (ESMO): Thyroid cancer, Clinical Practice Guidelines for Diagnosis, Treatment and Follow-up. 2019.

    National Institute for Health and Care Excellence (NICE). TA535: Lenvatinib and Sorafenib for treating differentiated thyroid cancer after radioactive iodine. 2018. www.nice.org.uk/guidance/ta535 [accessed May 2021].

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Nick Reed, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We try to make sure our information is as clear as possible. We use plain English, avoid jargon, explain any medical words, use illustrations to explain text, and make sure important points are highlighted clearly.

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