Sarcomas are cancers of connective tissue - bone, muscle, nerves, fatty tissue, cartilage etc. It can arise anywhere in the body, frequently hidden deep in the limbs. There are more than 50 subtypes of sarcoma, and there are two basic categories of sarcoma: soft tissue sarcoma and bone and joint sarcoma. They are rare, accounting for slightly more than 1% of all cancer diagnoses.Sarcomas are often misdiagnosed; sometimes they are thought to be sports injuries. When they are diagnosed, they may be large and difficult to remove surgically and they may have metastasized.
The causes of most sarcomas are unknown. There are some hereditary syndromes which have a pre-disposition to sarcoma but the number of cases is very small. Patients who had retinoblastoma (an eye cancer) as a child have a genetic defect which also gives them a pre-disposition to sarcoma in later life. People with neurofibromatosis type 1 (NF1) may have a tendency to develop sarcoma. There is evidence from the USA that prolonged or intensive exposure to certain chemicals (defoliants such as Agent Orange, used in the Vietnam War) may be a cause. Occasionally patients who have had radiotherapy for another cancer are diagnosed with sarcoma. Such radiation induced sarcomas (often angiosarcoma) can occur many years after the treatment for the first cancer and it is a matter of concern that the success in treating cancers such as breast cancer with radiation may create a small rise in cases of sarcoma.
Accurate data about the incidence of sarcoma is hard to find because cancer is reported against 'site of origin'. Sarcomas can appear almost anywhere on or in the body and many are only found following investigations for a condition which seems unconnected with cancer. They are often reported as a cancer associated with a specific part of the body rather than as a sarcoma. This means that it is uncertain what the actual number of cases is.
Approximate incidence figures are: