Generally, the cause of most soft tissue sarcomas is unknown. One of the few soft tissue sarcomas that has a known cause is Kaposi's sarcoma. It occurs in people with defective immune systems and is caused by a virus known as human herpes virus 8 (HHV-8).

Additionally, in some cases, sarcomas may be hereditary, such as in:

  • Basal cell nevus syndrome. In addition to an increased risk of basal cell skin cancer, people with this disorder are more likely to develop rhabdomyosarcoma or fibrosarcoma. It's caused by a genetic defect.
  • Inherited retinoblastoma. This rare form of childhood eye cancer may increase a child's risk of soft tissue sarcoma and is due to inheritance of a mutated retinoblastoma gene.
  • Li-Fraumeni syndrome. This condition is characterized by an increased risk of many malignancies, including sarcomas, breast cancer, brain cancer and others. People with this syndrome appear to be particularly susceptible to the side effects of radiation therapy.
  • Gardner's syndrome. This hereditary disease leads to precancerous and cancerous growths in the intestines and abdomen.
  • Neurofibromatosis. This condition results in developmental changes in the nervous system, causing nerve sheath tumors. About 1 in 20 people with neurofibromatosis develops malignant tumors.
  • Tuberous sclerosis. Benign tumors, seizures and learning problems are common with this disease, as is an increased risk of rhabdomyosarcoma.
  • Werner's syndrome. A defect in the gene RECQL2 causes numerous health problems, including an increased risk of soft tissue sarcomas.

Radiation exposure

Radiation is occasionally associated with sarcomas. These have usually occurred as a side effect of radiation therapy given for other cancers, such as breast cancer or lymphoma. Such serious side effects may become less common as radiation therapy offers more refined dosing strategies and more precise tumor targeting.

Chemical exposure

Another factor that may increase your risk of soft tissue sarcoma is exposure to high doses of chemicals such as:

  • Vinyl chloride, used in making plastics
  • Dioxin, an unwanted byproduct of incineration
  • Herbicides that contain the chemical phenoxyacetic acid
Sep. 13, 2011