What are the grades and stages of thyroid cancer?

Cancer grading diagram

What are the grades of thyroid cancer?

Grading describes how quickly the cancer may grow and spread. 

  • Low-grade thyroid cancer: The cancer cells look only slightly abnormal, much like normal thyroid cells. The cancer is usually slow-growing and less likely to spread than high-grade thyroid cancer.
  • High-grade thyroid cancer: The cancer cells look fairly or very abnormal and are more likely to grow quickly.

Grading describes the cancer cells – what they look like and how they might grow. Staging describes where the cancer is in your body.

What are the stages of thyroid cancer?

Staging means finding out how big the cancer is and if it has spread to other parts of your body. Staging will help your doctor to plan the best treatment for you.

The staging system normally used in thyroid cancer is called TNM. This stands for:

  • Tumour (T): How big is the tumour?
  • Node (N): Is there cancer in your lymph nodes?
  • Metastasis (M): Has the cancer spread to other parts of your body?

Your doctor often uses this information to give your cancer a number stage – from 1 to 4.

A higher number, such as stage 4, means a more advanced cancer. Some stages are further divided into stage A and B. 

Thyroid cancer can be stages slightly differently in some cases. This may depend on the type of cancer and your age.

Assessing your risk of recurrence

The TNM system does not fully predict the risk of the disease coming back (recurrence). Your doctor will look at many other factors - such as the make-up of the tumour - to assess your risk of recurrence. This is called risk stratification and will help your doctor decide what further treatment you need.

Stage 2 thyroid cancer diagram

Staging can be hard to understand, so ask your doctor and nurse for more information if you need it.

For more information

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