Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body. Usually, this information is acquired by doing diagnostic tests. Knowing the cancer’s stage can help plan out a treatment course and predict a patient’s prognosis.
There are different stage descriptions used for different types of sarcoma.
TNM System
One tool that doctors use to describe the stage is the TNM system. Doctors use the results from diagnostic tests and scans to answer these questions:
- Tumour (T): How large is the primary tumour? Where is it located?
- TX: The primary tumour cannot be evaluated.
- T0: There is no evidence of a primary tumour.
- T1: The tumour is 5cm or smaller.
- T2: The tumour is 5-10cm.
- T3: The tumour is 10-15cm.
- T4: The tumour is larger than 15cm.
- Node (N): Has the tumour spread to the lymph nodes? If so, where and how many?
- N0: The cancer has not spread to regional lymph nodes.
- N1: The cancer has spread to regional lymph nodes.
- Metastasis (M): Has the cancer metastasized to other parts of the body? If so, where and how much?
- M0: The cancer has not metastasized.
- M1: There is metastasis to another part of the body.
The results are combined to determine the stage of cancer for each person. There are 4 stages: stages I through IV (1 through 4). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
Grading
Doctors also describe soft tissue sarcoma based on its grade, which describes how much cancer cells look like healthy cells when viewed under a microscope. If the cancer resembles healthy tissue, it is called “differentiated” or “low-grade”. If the cancerous tissue looks very different from healthy tissue, it is called “poorly-differentiated” or “high-grade”. In general, a lower tumour grade indicates a better prognosis.
Staging
By combining the T, N, M, and grading classifications, doctors can assign a stage to the soft tissue sarcoma.
Stage IA: The tumor is smaller than 5 cm. It has not spread to lymph nodes or to other parts of the body (T1, N0, M0, low-grade).
Stage IB: The tumor is larger than 5 cm. It has not spread to lymph nodes or to other parts of the body (T2, T3, or T4; N0, M0, low-grade).
Stage II: The tumor is smaller than 5 cm. It has not spread to lymph nodes or to other parts of the body. The grade is higher than stage IA (T1, N0, M0, high-grade).
Stage IIIA: The tumor is 5 cm-10 cm. It has not spread to lymph nodes or to other parts of the body. The grade is higher than stage IB (T2, N0, M0, high-grade).
Stage IIIB: Either of the following applies:
- The tumor is larger than 10 cm. It has not spread to the regional lymph nodes or to other parts of the body. The grade is higher than stage IB (T3 or T4, N0, M0, high-grade).
- The tumor is located in the retroperitoneum and is any size. It has spread to the regional lymph nodes but not to other parts of the body (any T, N1, M0, any grade).
Stage IV: The tumor is any size, any grade, and may or may not have spread to the regional lymph nodes. It has spread to other parts of the body (any T, any N, M1, any grade).
Information taken from Cancer.net.