Ewing sarcoma is the second most common type of bone tumour to affect children, after osteosarcoma.
Whilst almost all cases of osteosarcoma occur in either the long bones of the legs (the femur and tibia) or the long bone of the arms (the humerus), Ewing sarcoma occurs in a broader range of sites.
Ewing sarcoma is actually a group of four different types of cancer, known collectively as the Ewing family of tumours (EFT). Ewing sarcoma of bone is the most common of these. Extraosseous Ewing sarcoma occurs in the soft tissue surrounding bone; peripheral primitive neuroectodermal tumour (PNET) can be found in either the bone or the soft tissue and Askin tumour occurs in the chest wall.
The cause of EFTs is unknown but it is thought that they may be linked to periods of rapid bone growth, explaining why they are seen more often in teenagers.
Ewing tumours of bone account for 37 per cent of the bone tumours occurring in children. Up to 25 children per year are diagnosed in the UK.
Up to 40 per cent of childhood Ewing sarcomas occur in the femur and tibia. Substantial numbers of cases arise in the pelvis (23 per cent), long bones of the arms (11 per cent), ribs, sternum and clavicle (9 per cent) and spinal column (8 per cent).
Ewing sarcoma has a lower incidence in children than osteosarcoma. The majority of cases are in the 10 to 14 year age group but the predominance of older children is less pronounced than for osteosarcoma. Up to the age of 6 years, Ewing sarcoma is the most common type of malignant bone tumour.
Incidence is similar in boys and girls up to age 10 when a male excess begins to emerge. This male excess emerges later in osteosarcoma (around 15 to 16 years).
In addition to the Ewing tumours of bone, around 16 children a year are diagnosed with the soft tissue types of Ewing sarcoma.
The overall five year survival rate for Ewing sarcoma of bone is 68 per cent. For extraosseous tumours, the survival rate is lower at 58 per cent.
An individual’s prognosis depends on the size of the tumour, site, whether it has spread and response to treatment.
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