- Family of cancers with common biology and treatment:
- Ewing sarcoma of bone
- Extraskeletal Ewing sarcoma (arises in soft tissue adjacent to bone)
- Peripheral neuroectodermal tumor (PNET) of bone or soft tissue
- Askin tumor (Ewing sarcoma of the chest wall)
- Most common primary tumor sites are as follows:
- Pelvic bones (26%)
- Femur (20%)
- Chest wall (16%)
- Second most common primary bone cancer of children and young adults after osteosarcoma
- Median age of diagnosis is 15 years, although can occur in any age group
- Slight male predominance
- ~200 to 250 new cases are diagnosed in the United States each year.
- Annual incidence in the United States of 2.7 cases per million children <15 years of age
- Most (~65%) occur in the 2nd decade of life.
- Striking racial difference in incidence: much lower incidence in African American and Asian populations compared to Caucasian population
- Most cases occur sporadically.
- Not associated with familial cancer syndromes
- Only rarely reported as a second malignancy
- One genome-wide association study identified several single nucleotide polymorphisms (SNPs) associated with higher risk.
- Epidemiologic studies suggest higher risk in patients with history of inguinal or umbilical hernia.
There are no known preventive measures.
- Rearrangement of the EWSR1 gene on chromosome 22 is detected in >95% of cases.
- 85% of cases have a t(11;22) translocation resulting in a fusion EWS-FLI1 protein.
- 10% of cases have a t(21;22) translocation between EWSR1 and ERG.
- Other translocation partners occur in <1% of cases and include other members of the ETS transcription factor family, such as ETV1.
- Fusion proteins thought to play a role as aberrant transcription factor
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