Ewing sarcoma is a rare bone tumor that occurs most often in adolescents.
It can also arise outside of the bone in soft tissue (extraosseous Ewing sarcoma). Ewing sarcoma is related to another type of tumor known as primitive neuroectodermal tumor (PNET). Researchers have learned that these tumors are associated with the same chromosomal abnormality (balanced reciprocal translocation) and share many physiological characteristics. Consequently, these tumors are sometimes collectively classified as the Ewing family of tumors (EFT). This general term encompasses Ewing sarcoma of bone, extraosseous Ewing sarcoma, primitive neuroectodermal tumor, and Askin’s tumor (a tumor of the chest wall). Ewing sarcoma of bone accounts for approximately 70 percent of the tumors in this family. Generally, the term Ewing sarcoma is preferred because, despite the different names, it is one tumor, molecularly. Ewing sarcoma of bone most often affects the long bone of the legs (femur) and flat bones such as those found in the pelvis and chest well. Ewing sarcoma is an aggressive cancer that may spread (metastasize) to the lungs, other bones, and bone marrow potentially causing life-threatening complications.
The exact cause of these tumors is unknown.
Ewing sarcoma was first described in the medical literature in 1921 by Dr. James Ewing. Ewing sarcoma is the second most common primary bone tumor in children and accounts for approximately 4% of all childhood cancer diagnoses.
The National Cancer Institute offers comprehensive, in-depth information about Ewing sarcoma
Synonyms & Subdivisions of Ewing Sarcoma
Ewing family of tumors
tumor of the Ewing family or TEF
- Askin’s tumor
- Ewing sarcoma of bone
- extraosseous Ewing (EOE) sarcoma
- primitive neuroectodermal tumor (PNET)
Causes of Ewing Sarcoma
The exact cause of Ewing sarcoma is unknown and the underlying cell type has not been identified. Most cases are thought to occur randomly, for no specific reason (sporadically).
Chromosomal (cytogenetic) studies have found that Ewing sarcoma cells are often characterized by an abnormal change in their genetic makeup known as a reciprocal translocation. A reciprocal translocation means pieces of two separate chromosomes break off and “trade places”. Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Pairs of human chromosomes are numbered from 1 through 22, and an additional 23rd pair of sex chromosomes which include one X and one Y chromosome in males and two X chromosomes in females. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered.
In Ewing sarcoma, the chromosomal areas involved are the long arms (q) of chromosome 11 and 22 (11q24-22q12). These pieces break off and trade places. In most cases, this results in the abnormal fusion of two genes, usually the EWS and FLI genes. Genes normally produce (encode) proteins that have several functions within the body. The abnormal fusion of the EWS and FLI genes results in a “fusion” gene that produces an abnormal protein product. Researchers believe that this abnormal protein may contribute to or influence the development of Ewing sarcoma, although, currently, the exact functions or impact of this protein is not fully understood. The reason that the chromosomal translocation between chromosomes 11 and 22 occurs is also unknown. According to some estimates, however, more than 85 percent of tumors in the Ewing family of tumors have this translocation. Less often, the EWS gene may fuse with another gene other than the FLI gene; these are often genes from the same family as FLI1, most often involving the gene ERG.
In extremely rare cases, Ewing sarcoma may develop as a second malignancy, which means that the disorder develops as a late-onset complication of earlier treatment for another form of cancer.
Ewing sarcoma affects males more often than females. It may affect individuals of any age, but most often occurs in individuals between 10 and 20 years of age. The annual incidence of Ewing sarcoma is 2.93 children per 1,000,000. Approximately 200-250 children and adolescents in the United States are diagnosed with a tumor in the Ewing family of tumors each year. Two-thirds will be long-term survivors (more than five years). The tumor occurs with greater frequency in Caucasians. It is extremely rare in African Americans and Asians.
Studies have shown that there are distinct differences between extraosseous (extraskeletal) Ewing sarcoma (EOE) and Ewing sarcoma of bone. EOE is more likely to occur in individuals above the age of 35 or below the age of 5, with a higher mean age than Ewing sarcoma of bone.
Standard Ewing Sarcoma Therapies
The therapeutic management of individuals with Ewing sarcoma may require the coordinated efforts of a team of medical professionals, such as physicians who specialize in the diagnosis and treatment of cancer in children (pediatric oncologists), adult oncologists, specialists in the use of radiation to treat cancer (radiation oncologists), surgeons, (orthopedic surgeons), oncology nurses, and other specialists (depending upon the primary tumor site).
Specific therapeutic procedures and interventions may vary, depending upon numerous factors, such as primary tumor location, extent of the primary tumor (stage), and degree of malignancy (grade); whether the tumor has spread to lymph nodes or distant sites; individual’s age and general health; and/or other elements. Decisions concerning the use of particular interventions should be made by physicians and other members of the health care team in careful consultation with the patient, based upon the specifics of his or her case; a thorough discussion of the potential benefits and risks; patient preference; and other appropriate factors.
Individuals with Ewing sarcoma and their families are encouraged to seek counseling after a diagnosis and before treatment because the diagnosis can cause anxiety, stress, and extreme psychological distress. Psychological support and counseling both professionally and through support groups is recommended for affected individuals and their families.
Individuals with a tumor in the Ewing family of tumors are treated with multiple anticancer drugs (chemotherapy) in combination with surgical procedures and/or radiation. Surgical removal of the malignancy and affected tissue or radiation is used to treat the primary tumor site. Chemotherapy kills cancer cells in the primary site as well as hidden cancer cells that may have spread into other areas of the body. Generally, systemic chemotherapy is administered first, followed by surgery or radiation. Surgery or radiation therapy without adjuvant chemotherapy has been far less effective than combination therapy. Radiation is often used to treat tumors that are inoperable and sometimes for metastatic disease.
Physicians use multiple chemotherapeutic drugs because different drugs have different modes of action in destroying tumor cells and/or preventing them from multiplying. Chemotherapy drugs often used to treat individuals with Ewing sarcoma include doxorubicin, vincristine, cyclophosphamide, dactinomycin, ifosfamide, and etoposide.
Investigational Ewing Sarcoma Therapies
Information on current clinical trials is available at http://clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
History of Ewing Sarcoma
Click above to read more about Dr. James R. Ewing, “a pioneer in the field of cancer research, and whose vision continues to steer our cancer research enterprise nearly a century later.”
One of our goals as a Foundation is to provide information about Ewing sarcoma research and resources. Through the expert eyes of our Medical Advisory Board, we strive to bring attention to Ewing sarcoma and provide critical information to patients, families, and anyone with the means to join the fight.