What are the grades and stages of soft tissue sarcoma?

Doctor talking to a male patient

How is soft tissue sarcoma graded and staged?

Your doctor will want to know the stage and grade of your soft tissue sarcoma. This information helps them to decide on the best treatment for you.

Grading sarcoma

The grade of a cancer describes how abnormal the cells look under the microscope compared to normal, healthy cells and how the cancer might behave – for example, how quickly it might grow and how it might respond to treatment. The cells are taken during a biopsy.

  • Low-grade cancer cells look similar to normal cells and are less likely to spread.
  • High-grade cancer cells look very different from normal cells and may grow quickly.

Soft tissue sarcomas are graded from 1 to 3 using a classification system known as the French Federation of Cancer Centers Sarcoma Group (FNCLCC) system.

This system looks at:

  1. Mitotic score (this is a score of how many cells are actively dividing within the tumour).
  2. Necrosis score (this refers to how many tumour cells are beginning to die off within the tumour)
  3. Tumour differentiation score (this is a measure of how closely the tumour resembles normal tissues. For example, a low grade leiomyosarcoma will be made up of cells that look like normal smooth muscle cells).

Each area has a score of 1, 2 or 3. The final grade is calculated by adding up the scores for each area.

  • Grade 1 = Overall score of 2 or 3 (for example, mitotic score 1 + necrosis score 1 = 2)
  • Grade 2 = Overall score of 4 or 5
  • Grade 3 = Overall score of 6 or more.

A lower grade (grade 1) means the cancer is less likely to grow and spread.  

Staging sarcoma

Sarcoma staging looks at where the tumour is, how big it is and if it’s spread to lymph nodes or other parts of the body. For example, sarcomas involving the trunk (chest, tummy (abdomen) and back) and extremities (arms and legs) are staged using the TNM system:

Tumour (T) describes the size of the original tumour. 

  • T1 means the tumour is 5cm or less across.
  • T2 means it is greater than 5 cm. 
  • The letter ‘a’ (T1a, T2a) indicates that the tumour is near the surface of the body
  • The letter ‘b’ (T1b, T2b) indicates it is deeper in the body.

Node (N) indicates whether the cancer is present in the regional lymph nodes. 

  • N0 indicates that the tumour has not spread to the lymph nodes.
  • N1 means that it has spread to the lymph nodes.

Metastasis (M) refers to whether the cancer has spread to other parts of the body. 

  • M0 means that the tumour has not spread
  • M1 indicates that the tumour has spread to other parts of the body.

Number stages

The T, N and M ratings are combined with the grade to determine the number stage of soft tissue sarcoma: stage 0 to stage 4. Determining the patient’s exact stage of soft tissue sarcoma is extremely important in developing his or her treatment plan. Other factors, such as the type and location of the sarcoma, will also play a role in developing an individualised treatment plan.

Stage 1

This stage has two subcategories:

  • Stage 1A: The tumour is smaller than 5cm across and has not spread to the lymph nodes or to distant sites. At this stage, the cancer is considered grade 1, or it cannot be assessed.
  • Stage 1B: The tumour is larger than 5cm across and has not spread to the lymph nodes or distant sites. It is either grade 1 or cannot be assessed.

Stage 2

This stage has two subcategories:

  • Stage 2A: The tumour is not larger than 5cm across, and it has not spread to the lymph nodes or distant sites. The cancer is grade 2 or 3.
  • Stage 2B: The tumour is larger than 5cm across and has not spread to the lymph nodes or distant sites. The cancer is grade 2.

Stage 3

  • The tumour is larger than 5cm across and has not spread to the lymph nodes or distant sites. The cancer is grade 3.
  • The tumour can be any size, and it has spread to nearby lymph nodes but not distant sites. The cancer can be any grade.

Stage 4

The tumour can be any size and any grade. It may or may not have spread to the lymph nodes, but it is has spread to distant sites.

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

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