It is recommended that classification of soft tissue sarcoma in the abdomen and pelvis is done according to WHO guidelines. The American Joint Committee on Cancer (AJCC)/International Union Against Cancer (UICC) staging classification system is based on several factors. Its use in routine clinical practice is limited.
The TNM system describes the extension of the disease at presentation.
- (T) size of the tumor
- (N) whether or not the sarcoma cells have spread to the lymph nodes, which in most soft tissue sarcoma patients is very rare
- (M) whether or not the sarcoma cells have spread or metastasized to other parts of the body
The AJCC/UICC system also stresses the histopathological or malignancy grading. This component assesses how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. It is also often called tumor grade.
A four-point scale has been commonly used until recently:
- Grade I and II are low-grade malignant (constitute about 30% of all tumors)
- Grade III and IV are high-grade malignant (constitute about 70% of all tumors)
It is becoming more common to use a three-point scale (French system) where grade 3 is the most aggressive.
Other histopathological factors that are not part of the staging system but may be important for prognosis of soft tissue sarcomas include growth pattern, necrosis and vessel invasion.
The staging system used for gynecological sarcomas is the same as for endometrial cancer (FIGO). Specific staging of gynecological sarcomas is under development.