Ewing Tumor Stages

Once a Ewing tumor has been diagnosed, tests are done to determine the stage (extent of spread) of the cancer. The stage of a Ewing tumor describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

The stage is based on results of imaging tests and biopsies of the main tumor and other tissues, which are described in Tests for Ewing Tumors

A staging system is a standard way for the cancer care team to sum up the extent of the cancer. The formal (and more detailed) staging system for Ewing tumors is the American Joint Committee on Cancer (AJCC) system for bone cancer. It is described below to help you understand it, in case your doctor refers to it. But for treatment purposes, doctors often use a simpler system, dividing Ewing tumors into 2 groups: localized or metastatic.

Staging can be confusing. If you have any questions about the stage of the cancer, ask someone on the health care team to explain it to you in a way you understand.

Localized vs. metastatic stages

When determining how best to treat a Ewing tumor, doctors typically classify them as either localized or metastatic.

Localized Ewing tumors

Doctors call a Ewing tumor "localized" if they believe it's only in the area where it started or in nearby tissues such as muscle or tendons. A Ewing tumor is considered localized only after all of the imaging tests (x-rays, CT or MRI scans, and PET or bone scans) and the bone marrow biopsy and aspirate (if done) do not find it has spread to distant parts of the body.

Even when imaging tests do not show that the cancer has spread to distant areas, most patients are likely to have micrometastases (very small areas of cancer spread that can’t be detected with tests). This is why chemotherapy, which can reach all parts of the body, is an important part of treatment for all Ewing tumors.

Metastatic Ewing tumors

A metastatic Ewing tumor has clearly spread from where it started to distant parts of the body. Most of the time, it spreads to the lungs or to other bones or the bone marrow. Less commonly, it spreads to the liver or lymph nodes.

About 1 in 5 patients will have obvious spread that is found by imaging tests. But as mentioned above, many other patients are likely to have small amounts of cancer spread to other parts of the body that can’t be seen on imaging tests.

AJCC staging system for bone cancer

The AJCC uses one system to describe all bone cancers, including Ewing tumors that start in bone.

Extraosseous Ewing (EOE) tumors (Ewing tumors that don’t start in bones) are staged differently. They are staged like soft tissue sarcomas. Information about soft tissue sarcoma staging can be found in Sarcoma - Adult Soft Tissue Cancer.

The AJCC staging system for bone cancers is based on 4 key pieces of information:

  • T describes the size of the main (primary) tumor and whether it appears in different areas of the bone.
  • N describes the extent of spread to nearby (regional) lymph nodes (small bean-sized collections of immune system cells). Bone tumors rarely spread to the lymph nodes.
  • M indicates whether the cancer has metastasized (spread) to other organs of the body. (The most common sites of spread are to the lungs or other bones.)
  • G stands for the grade of the tumor, which describes how the cells from biopsy samples look. Low-grade tumor cells look more like normal cells and are less likely to grow and spread quickly, while high-grade tumor cells look more abnormal. (All Ewing tumors are considered high-grade tumors.)

Numbers or letters after T, N, M, and G provide more details about each of these factors.

T categories of bone cancer*

  • T0: There is no evidence of a main (primary) tumor.
  • T1: The tumor is no more than 8 cm (around 3 inches) across.
  • T2: The tumor is larger than 8 cm across.
  • T3: The tumor is in more than one site in the same bone.

*The T categories are slightly different if the main tumor is in the pelvis (hip bone) or spine.

N categories of bone cancer

  • N0: There is no spread to nearby lymph nodes.
  • N1: The cancer has spread to nearby lymph nodes.

M categories of bone cancer

  • M0: There is no spread (metastasis) to distant organs.
  • M1a: The cancer has spread only to the lungs.
  • M1b: The cancer has spread to other distant parts of the body.

Grades of bone cancer

  • GX: Grade can’t be assessed
  • G1: Low grade
  • G2-G3: High grade

(All Ewing tumors are considered G3.)

Stage grouping

Once the T, N, and M categories and the grade of the bone cancer have been determined, the information is combined and expressed as an overall stage. The process of assigning a stage number is called stage grouping. The stages are described in Roman numerals from I to IV (1-4), and are sometimes divided further.

Stage IA*

T1, N0, M0, G1 (or GX): The tumor is no more than 8 cm across (T1) and is low grade (or the grade can’t be assessed). The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).

Stage IB*

T2 or T3, N0, M0, G1 (or GX): The tumor is either larger than 8 cm across (T2) or it is in more than one place in the same bone (T3). It is low grade (or the grade can’t be assessed). The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).

Stage IIA

T1, N0, M0, G2 to G3: The tumor is no more than 8 cm across (T1) and is high grade (G2 or G3). The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).

Stage IIB

T2, N0, M0, G2 to G3: The tumor is larger than 8 cm across (T2) and is high grade (G2 or G3). The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).

Stage III

T3, N0, M0, G2 to G3: The tumor is in more than one place in the same bone (T3). It is high grade (G2 or G3). The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).

Stage IVA

Any T, N0, M1a, any G: The tumor has spread only to the lungs (M1a). It has not spread to the lymph nodes (N0) or to other parts of the body. (It can be any size or grade.)

Stage IVB (if either of these applies)

Any T, N1, any M, any G: The tumor has spread to nearby lymph nodes (N1). It can be any size or grade, and may or may not have spread to other parts of the body.

Any T, any N, M1b, any G: The tumor has spread to distant parts of the body other than the lungs (M1b). It can be any size or grade.

*All Ewing tumors are classified as G3 (high grade), so they are never stage I bone cancers.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Joint Committee on Cancer. Bone. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017: 471-486.

Anderson ME, Randall RL, Springfield DS, Gebhart MC. Chapter 92: Sarcomas of bone. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 5th ed. Philadelphia, Pa: Elsevier; 2014.

DeLaney TF, Hornicek FJ. Clinical presentation, staging, and prognostic factors of the Ewing sarcoma family of tumors. UpToDate. Accessed at www.uptodate.com/contents/clinical-presentation-staging-and-prognostic-factors-of-the-ewing-sarcoma-family-of-tumors on March 5, 2018.

National Comprehensive Cancer Network (NCCN). Practice Guidelines in Oncology: Bone Cancer. Version 1.2018. Accessed at www.nccn.org/professionals/physician_gls/pdf/bone.pdf on March 5, 2018.

Last Medical Review: May 31, 2018 Last Revised: May 31, 2018

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