Sarcomas are cancers that arise from the background supporting cells of the body - the mesenchyme - (in contrast to the more common: carcinomas that arise from lining epithelial cells).
They are less frequent in incidence (perhaps 1% of all cancers) but important in that they often occur in younger ages (there are two age peaks: childhood and past 55 years) and can be curable, if caught early and treated correctly.
As has been said, the incidence is perhaps 1% of cancer overall, and the majority occur without predisposing recognised syndromes.
There is an unequal distribution of anatomic sites from which sarcomas arise: thus, the lower limbs are the commonest site of origin of soft tissue sarcomas in adults, followed by the upper limbs, the torso and then the head and neck region and retroperitoneum.
The disease is slightly more common in males. This contrasts with the incidence of childhood where the disease accounts for 8% of all childhood cancer and the tumours are very much most commonly rhabdomyosarcomas and the distribution is 1/3 in the genitourinary system, 1/3 in the head and neck region and 1/3 in the rest of the body.