Ewing Sarcoma: Stages

What does the stage of a cancer mean?

The stage of a cancer is how much and how far the cancer has spread in the body. Your healthcare provider uses exams and tests to find out the size of the cancer and where it is, He or she can also see if the cancer has spread to nearby areas, or if it has spread to other parts of the body. The stage of a cancer is one of the most important things to know when deciding how to treat the cancer.

How is Ewing sarcoma staged?

Different staging systems can be used for Ewing sarcoma.

Localized versus metastatic cancer

For practical purposes (including deciding on treatment), healthcare providers often use a simple system that divides Ewing tumors into one of two groups:

• Localized cancer. The cancer seems to be only in the tissue (such as bone or muscle) where it started or in nearby tissues. It doesn’t seem to have 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 there. This is why chemotherapy, which can kill cells anywhere in the body, is an important part of the treatment for Ewing sarcoma.

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

The TNM staging system

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

• T describes the size of the tumor and if it is in different areas of the bone.

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

• M describes whether 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 scale from 1 to 4. Lower grade cancers look more like normal cells and are likely 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.

Stage groupings are determined by combining these four factors. These groupings give an overall description of your cancer. A stage grouping is listed as a Roman numeral and can have a value of I through IV (1 through 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.

What are the TNM stage groupings for Ewing sarcoma?

These are the stage groupings of Ewing sarcoma using the TNM system and what they mean:

Stage I. Cancer in this stage is divided into these two groups:

• Stage IA. The cancer is 8 centimeters (cm) or less across, or it's in more than one spot in the same bone. It's either low grade or the grade isn't known. The cancer hasn't spread to nearby lymph nodes or distant organs in the body.

• Stage IB. The cancer is more than 8 cm across, or it's in more than one spot in the same bone. It's either low grade or the grade isn't known. The cancer hasn't spread to nearby lymph nodes or distant organs in the body.

Because all Ewing sarcomas are high grade, they are never Stage IA or IB.

Stage II. Cancer in this stage is divided into these two groups:

• Stage IIA. The cancer is 8 cm or less across and is high grade. The cancer hasn't spread to nearby lymph nodes or distant organs in the body.

• Stage IB. The cancer is more than 8 cm across and is high grade. The cancer hasn't spread to nearby lymph nodes or distant organs in the body.

Stage III. The cancer is in more than one spot in the same bone and is high grade. The cancer hasn't spread to nearby lymph nodes or distant organs in the body.

Stage IV.  Cancer in this stage is divided into these two groups:

• Stage IVA. The cancer has spread to the lungs, but not to lymph nodes or distant organs in the body. It can be any size or grade.

• Stage IVB.  The cancer is either of these:

  • The cancer has spread to lymph nodes. It may or may not have spread to distant organs in the body. It can be any size or grade.

  • The cancer has spread to distant organs other than the lungs. It can be any size or grade.

Talking with your healthcare provider

Once the cancer is staged, talk with your healthcare provider about what the stage means for you. Make sure to ask questions and talk about your concerns.