Epidemiology
Sarcomas are tumours of the body’s supportive connective tissue and can arise from bone, muscle, cartilage, tendon, fat, or synovial tissue. They account for less than 1% of all cancers. Ewing’s sarcoma and osteosarcoma develop primarily in children and adolescents, and occurrence appears to correlate with the growth spurt.
Soft tissue sarcomas are rare in adults, but account for approximately 6% of all childhood cancers.
Aetiology
For the majority of bone sarcomas no specific aetiology has been established, although predisposing factors have been identified. Children with familial retinoblastoma have a 13q chromosome deletion and an increased incidence of osteosarcoma (see Chapter 8). Radiation-associated sarcomas develop within a radiation field usually after a latent period of at least 3 years and the majority are osteosarcoma. Alkylating agents and anthracyclines have been implicated in the development of second malignancies, particularly osteosarcoma. In adults, osteosarcoma is often associated with an underlying bone abnormality such as Paget’s disease, fibrous dysplasia, or where the bone has been irradiated previously.
For soft tissue sarcomas, there is a genetic association with neurofibromatosis type 1, hereditary retinoblastoma and Li–Fraumeni syndrome. Previous radiation therapy increases the risk of developing sarcoma and exposure to chemicals such as vinyl chloride monomer, dioxin, or herbicides are risk factors for developing sarcomas (see Chapter 3).
Ewing’s sarcoma typically arises from the axial skeleton and is associated with the t(11;22) chromosomal translocation. This chromosomal alteration juxtaposes the EWS and FLI1 genes, producing a hybrid transcript that is able to act as a master regulatory protein.
Clinical presentation
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