Incidence and epidemiology of soft tissue sarcoma

Soft tissue sarcomas occur with an incidence of 30 per million and represent less than 1% of all malignancies. They can occur in almost any anatomic site, but tend to occur with a frequency that reflects the volume of mesechymal-derived tissue in that region.  For example, around 55% occur in the limbs. The type of tumour varies with age: rhabdomyosarcoma is a disease of early life, whereas leiomyosarcoma is more common in the elderly.

Environmental factors associated with sarcoma include:

  • Radiation (eg after therapeutic radiotherapy)
  • Immunodeficiency
  • Occupational (eg exposure to dioxins)

Genetic factors include

  • Li-Fraumeni syndrome (inherited p53 deficiency)
  • Neurofibromatosis.

Classification of soft tissue tumours

Soft tissue tumours are classified using the WHO classification, based on the morphological appearances of the tumour and whether or not it is benign or malignant. There are more than 50 variants of soft tissue sarcoma. The classification includes:

  • adipocytic tumours (eg lipoma, liposarcoma)
  • fibroblastic/myofibroblastic tumours (eg elastofibroma, adult fibrosarcoma)
  • so-called fibrohistiocytic tumours (eg GCT of tendon sheath, pleomorphic MFH)
  • smooth muscle tumours (eg angioleiomyoma, leiomyosarcoma)
  • pericytic tumours (eg glomus tumour)
  • skeletal muscle tumours (eg rahbdomyoma, rhabdomyosarcoma)
  • vascular tumours (eg haemangioma, angiosarcoma)
  • chondro-osseous tumours (eg soft tissue chondroma, extraskeletal osteosarcoma)
  • tumours of uncertain differentiation (eg intramuscular myxoma, synovial sarcoma)