Stages of Soft Tissue Sarcomas

After someone is diagnosed with a soft tissue sarcoma, doctors will try to figure out if it has spread, and if so, how far. This process is called staging.

The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

How is the stage determined?

The stages of soft tissue sarcomas range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. And within a stage, an earlier letter means a lower stage.

TNM system

The staging system most often used for soft tissue sarcomas is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 4 key pieces of information:

• The extent of the tumor (T): How large is the cancer?
• The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
• The spread (metastasis) to distant sites (M): Has the cancer spread to distant organs such as the lungs?
• The grade (G) of the cancer: How much do the sarcoma cells look like normal cells?

Grade

The grade is partly used to determine the stage of a sarcoma. The staging system divides sarcomas into 3 grades (1 to 3) based on features seen under a microscope.

Low-grade tumors tend to be slow-growing, slower to spread, and often have a better outlook (prognosis) than higher-grade tumors.

French (FNCLCC) system

The grade of a sarcoma is determined using a system known as the French or FNCLCC system, and is based on 3 factors.

Differentiation: Cancer cells are given a score of 1 to 3. Cells assigned a 1 look a lot like normal cells and cells assigned a 3 look very abnormal. Certain types of sarcoma, like synovial and embryonal sarcomas, are given a higher score automatically.

Mitotic count: A score 1 to 3 is given to describe how many cancer cells are seen dividing. A lower score means fewer cells were seen dividing.

Tumor necrosis: A score from 0 to 2 is given to describe how much of the tumor is made up of dying tissue. A lower score means there was less dying tissue present.

After each factor is given a score, the scores are added to determine the grade of the tumor. Here's what the grade numbers mean:

• GX: The grade cannot be assessed because of incomplete information.
• Grade 1 (G1): Total score of 2 or 3
• Grade 2 (G2): Total score of 4 or 5
• Grade 3 (G3): Total score of 6, 7, or 8

Pathologic vs. clinical stage

The staging system in the table below uses the pathologic stage, also called the surgical stage. It is determined by examining tissue removed during an operation.

Sometimes, if surgery is not possible right away or at all, the cancer will be given a clinical stage instead. This is based on the results of a physical exam, biopsy, and imaging tests. The clinical stage will be used to help plan treatment.

Sometimes, the cancer has spread further than the clinical stage estimates and might not predict the patient’s outlook as accurately as a pathologic stage.

Stage grouping

There are different staging systems for soft tissue sarcomas depending on where the cancer is in the body:

• Head and neck
• Trunk and extremities (arms and legs)
• Abdomen and thoracic (chest) visceral organs
• Retroperitoneum

Once a person’s T, N, M, and G categories have been determined, this information is combined in a process called stage grouping to assign an overall stage.

Retroperitoneum Sarcoma Stages

*The following categories are not listed in the staging groupings above:

• TX: Main tumor cannot be assessed due to lack of information.
• T0: No evidence of a primary tumor.
• NX: Regional lymph nodes cannot be assessed due to lack of information.