Staging systems provide doctors with a common language for describing tumors. After bone cancer is diagnosed, a series of tests are used to investigate the extent of the cancer and to see whether it has spread to other parts of the body from where it started.
Staging is a way of recording the size, aggressiveness and growth of a cancer, and determining the plan for treatment. By understanding the stage of your cancer, you can make informed decisions about your treatment.
Staging bone cancer attempts to discover the following:
- The size of the tumor
- Whether the cancer has spread to nearby lymph nodes and tissues
- Whether the cancer has spread to other parts of the body
Stages of Bone Sarcoma
Doctors use diagnostic tests to determine the cancer's stage. Staging may not be complete until all the tests are finished. Knowing the stage helps decide what kind of treatment is best and can help predict recovery.
One staging system, developed by the Musculoskeletal Tumor Society (MTS) in 1986 uses size and histologic grade (how different the cells look under the microscope when compared to normal cells) to determine the stage.
The American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC) developed a staging system that is more common and uses size and histologic grade in determining the stage.
- T stands for features of the tumor (size, location)
- N stands for spread to lymph nodes
- M stands for metastasis (spread)
T Stages of Bone Cancer
- TX: Primary tumor can't be measured
- T0: No evidence of the tumor
- T1: Tumor is 8 cm (around 3 inches) or less
- T2: Tumor is larger than 8 cm
- T3: Tumor is in more than one place on the same bone
N Stages of Bone Cancer
- N0: The cancer has not spread to the lymph nodes near the tumor
- N1: The cancer has spread to nearby lymph nodes
M Stages of Bone Cancer
- M0: The cancer has not spread anywhere outside of the bone or nearby lymph nodes
- M1: Distant metastasis (the cancer has spread)
- M1a: The cancer has spread only to the lung
- M1b: The cancer has spread to other sites (like the brain, the liver, etc.)
Grades of Bone Cancer
- G1-G2: Low grade
- G3-G4: High grade
TNM Stage Grouping
After the T, N, and M stages and the grade of the bone cancer have been determined, the information is combined to state the overall stage. The process of assigning a stage number is called stage grouping. To determine the grouped stage of a cancer using the AJCC system, find the stage number below that contains the T, N, and M stages, and the proper grade.
Stage I: All stage I tumors are low grade and have not yet spread outside of the bone.
- Stage IA: T1, N0, M0, G1-G2: The tumor is 8 cm or less.
- Stage IB: T2 or T3, N0, M0, G1-G2: The tumor is either larger than 8 cm or it is in more than one place on the same bone.
Stage II: Stage II tumors have not spread outside the bone (like Stage I) but are high grade.
- Stage IIA: T1, N0, M0, G3-G4: The tumor is 8 cm or less.
- Stage IIB: T2, N0, M0, G3-G4: The tumor is larger than 8 cm.
Stage III: T3, N0, M0, G3-G4: Stage III tumors have not spread outside the bone but are in more than one place on the same bone. They are high grade.
Stage IV: Stage IV tumors have spread outside of the bone they started in. They can be any grade.
- Stage IVA: Any T, N0, M1a, G1-G4: The tumor has spread to the lung.
- Stage IVB: Any T, N1, any M, G1-G4 OR Any T, any N, M1b, G1-G4: The tumor has spread to nearby lymph nodes or to distant sites other than the lung (or both).