Once a sarcoma is diagnosed, it is important to determine the stage or extent of the disease. Staging is a way of determining how much disease is in the body and where it has spread. This information is used in identifying the best type of treatment and the outlook for recovery (prognosis)
Once the staging classification is determined, the stage remains the same even if treatment is successful or the cancer spreads.
Soft Tissue Sarcoma Staging
The system often used to stage sarcomas is the TNM system of American Joint Committee on Cancer.
- T stands for the size of the tumor.
- N stands for spread to lymph nodes (small bean-shaped collections of immune system cells found throughout the body that help fight infections and cancers).
- M is for metastasis (spread to distant organs).
- In soft tissue sarcomas, an additional factor, called grade (G), is part of tumor stage. The grade is based on how the sarcoma cells look under the microscope.
The official soft tissue sarcoma staging system divides sarcomas into three grades (1 to 3). The grade of a sarcoma, which is used to determine its stage, helps predict how rapidly it will grow and spread, as well as a person’s prognosis.
How are soft tissue sarcomas graded?
The grade of a sarcoma is based on the way the cancer looks under the microscope. In grading a cancer, pathologists consider three factors:
- How closely the tumor resembles normal tissue (differentiation) on a scale of 1 to 3
- How many of the cells appear to be dividing, on a scale of 1 to 3 (mitotic count)
- How much of the tumor is made up of dying tissue (tumor necrosis)
These factors are scored and added together to determine the grade of the tumor. Sarcomas with cells looking more normal and with fewer cells dividing are generally placed in a low-grade category. Low-grade tumors are slow growing, slower to spread, and often have a better prognosis than higher-grade tumors. The grade is usually based on the way the cells look and how many are dividing, but certain types of sarcoma are automatically given higher scores for differentiation. This affects the overall score so much that they are never considered to be low grade. Examples of these include synovial sarcoma and embryonal sarcoma.
The scores for each factor are added up to determine the grade for the cancer. Higher-grade cancers tend to grow and spread faster than lower-grade cancers.
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 or higher
- T1: The sarcoma is 5 cm (2 inches) or less across
- T1a: The tumor is superficial -- near the surface of the body
- T1b: The tumor is deep in the limb or abdomen
- T2: The sarcoma is greater than 5 cm across
- T2a: The tumor is superficial -- near the surface of the body
- T2b: The tumor is deep in the limb or abdomen
- N0: The sarcoma has not spread to nearby lymph nodes
- N1: The sarcoma has spread to nearby lymph nodes
- M0: No distant metastases (spread) of sarcoma are found
- M1: The sarcoma has spread to distant organs or tissues (such as the lungs)
What Are the Stages of Sarcoma Cancer?
To assign a stage, information about the tumor, its grade, lymph nodes and metastasis is combined by a process called stage grouping. The stage is described by Roman numerals from I to IV with the letters A or B. The stage is useful in selecting treatment, but other factors, like location of the sarcoma, also impact treatment planning and outlook.
Sarcoma Cancer Stage IA (1A)
- T1, N0, M0, G1 or GX: The tumor is not larger than 5 cm (2 inches) across (T1). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 1 (or the grade cannot be assessed).
Sarcoma Cancer Stage IB (1B)
- T2, N0, M0, G1 or GX: The tumor is larger than 5 cm (2 inches) across (T2). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 1 (or the grade cannot be assessed)
Sarcoma Cancer Stage IIA (2A)
- T1, N0, M0, G2 or G3: The tumor is not larger than 5 cm (2 inches) across (T1). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 2 or 3.
Sarcoma Cancer Stage IIB (2B)
- T2, N0, M0, G2: The tumor is larger than 5 cm (2 inches) across (T2). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 2.
Sarcoma Cancer Stage III (3): Either
- T2, N0, M0, G3: It is larger than 5 cm (2 inches) across (T2). It has not spread to lymph nodes (N0) or more distant sites (M0). The cancer is grade 3, OR
- Any T, N1, M0, any G: The cancer can be any size (any T) and any grade. It has spread to nearby lymph nodes (N1). It has not spread to distant sites (M0)
Sarcoma Cancer Stage IV (4)
- Any G, Any T, Any N, M1: The tumor has spread to lymph nodes near the tumor (N1) and/or to distant sites (M1). It can be any size (any T) and grade (any G).