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4. Incidence and Etiology

Soft tissue sarcomas (STS) are rare tumours with an annual incidence of about 5 – 6 per 100,000 persons per year. They account for only 1% of all cancers. However, these tumours account for nearly 7% of cancer in children under 15.

The large majority of soft tissue sarcomas arise de novo, without an apparent causative factor, but some may be related to underlying inherited conditions or environmental factors. 

a) Inherited Conditions

Some inherited conditions are associated with an increased risk for the development of soft tissue sarcomas. Some examples include:

Pattern of Inheritance 
Associated Tumour(s)
Gastro-intestinal stromal tumour (GIST), paraganglioma
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Familial GIST
Osteosarcoma, rhabdomyosarcoma and other tumours
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Neurofibromatosis type 1
MPNST(malignant peripheral nerve sheath tumour), GIST, rhabdomyosarcoma
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Gardner syndrome (FAP variant)
Desmoid fibromatosis
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Osteosarcoma, rhabdomyosarcoma, leiomyosarcoma
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Young age at presentation and a personal and/or family history of cancer suggest an underlying germline mutation. It is important to identify these patients for genetic counselling and surveillance for other disease manifestations.

b) Radiation Exposure

Prior radiation treatment (for example in adjuvant treatment of breast cancer), is associated with increased risk of malignancy within the previous radiation field. The risk increases with the amount of radiation therapy given. The median latent interval (time between exposure and tumour diagnosis) is about 10 years. Chemotherapy given with radiation therapy may decrease the time to development of a radiation associated sarcoma.

c) Viral infection and immunodeficiency

Human immunodeficiency virus (HIV) and Human herpesvirus 8 have been implicated in the pathogenesis of Kaposi sarcoma. 

d) Chemical carcinogens

Due to rarity and difficulty in isolating a single agent, causal associations are difficult to prove. There have been documented associations between vinyl chloride or arsenic exposure with hepatic angiosarcoma.


  • Taghian A, Tubiana M, Long term risk of sarcoma following radiation treatment for breast cancer. Intl J of radiation Oncology Biology Physics. Vol 21, Jul1991.
  • Neglia et al. Second malignant neoplasms in 5 year survivors of childhood cancer: Childhood Cancer survivor study. JNCI 2001; 93 (9) 
  • Ferrari A, Sultan I, Huang TT, et al. Soft tissue sarcoma across the age spectrum: a population-based study from the Surveillance, Epidemiology, and End Results database. Pediatr Blood Cancer. 2011; 57:943–949.
  • Zhang AY, Judson I, Benson C, Wunder JS, Ray-Coquard I, Grimer RJ, Quek R, Wong E, Miah AB, Ferguson PC, Dufresne A, Teh JYH, Stockler M &  Tattersall MHN. Chemotherapy with radiotherapy influences time-to-development of radiation-induced sarcomas: a multicenter study. British Journal of Cancer volume117, pages326–331 (25 July 2017)

SOURCE: 4. Incidence and Etiology ( )
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