Ewing Sarcoma: Stages

For practical purposes (including deciding on treatment choices), healthcare providers use a simpler system. This divides Ewing tumors into two groups:

• Localized cancer.  The cancer seems to be only in the tissue (like bone or muscle) where it first started. It might also be in nearby tissues, such as lymph nodes. It hasn’t spread to other parts of the body based on imaging tests and bone marrow biopsies. But even if imaging tests don’t show cancer in other parts of the body, it's possible that small amounts of cancer may have spread to other places. This is why chemotherapy, which can kill cells anywhere in the body, is an important part of the treatment for Ewing sarcoma.

• Metastatic cancer.  The cancer has spread from where it started to other parts of the body. This might be the lungs, other bones, or bone marrow. Less often, it spreads to lymph nodes or the liver. 

Ewing sarcomas of the bone can also be staged using the TNM system from the American Joint Committee on Cancer. This is the same staging system that’s used for other types of bone cancers. This more detailed staging system is based on four key pieces of information:

• T notes the size of the  tumor and if it's in different parts of the same bone.

• N notes if the cancer has reached nearby lymph  nodes. This is rare for bone tumors.

• M notes if the cancer has spread ( metastasized) to distant parts of the body.

• G is the  grade of the tumor. This is a measure of how quickly the cancer is likely to grow and spread. It’s based on how the cancer cells look under the microscope. The cancer cells are graded on a 1 to 3 scale. Lower grade cancers look more like normal cells. They tend to grow and spread slowly. A higher-grade cancer is more likely to grow and spread quickly if not treated. All Ewing sarcomas are high-grade tumors.

The T, N, M, and G values from the TNM system are used to put these cancers into stage groupings. The groupings give an overall description of your cancer. A stage grouping is listed as a Roman numeral and can have a value of I (1), II (2), III (3), or IV (4). The higher the number, the more advanced the cancer is. Letters and numbers can be used after the Roman numeral to give more details.