Soft tissue sarcoma causes and risk factors

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on June 6, 2022.

Soft tissue sarcoma is a type of cancer that can affect any soft tissue in the body, including nerves, muscles, fat, blood vessels, skin tissue or fibrous tissue. This is a rare type of cancer that’s diagnosed in about 13,000 people in the United States each year.

What causes soft tissue sarcoma?

While the exact cause of soft tissue sarcoma isn’t known, this condition develops when cells located in the body’s soft tissues mutate, or change, causing them to divide and grow uncontrollably. The cells then form tumors that can grow, and may spread to other areas of the body.

Soft tissue sarcoma risk factors

Some common risk factors for soft tissue sarcoma include those listed below.

Age: While soft tissue sarcoma can occur in people of any age, it is more commonly found in adults over the age of 50.

Chemical exposure: Exposure to vinyl chloride and dioxin may increase the risk for developing soft tissue sarcomas. Vinyl chloride is used to make polyvinyl chloride (PVC) pipes, car upholstery, plastic kitchenware and wire coatings.

Dioxins are a group of chemicals that form during the burning of household and industrial waste. One notable type of dioxin is Agent Orange, an herbicide used in the Vietnam War to clear ground cover. Many veterans were exposed to Agent Orange. If the patient served in Vietnam, Thailand or the Korean Demilitarized Zone, it's important to know that there is evidence that soft tissue sarcomas are linked to chemical exposure. Speak with the care team or contact the U.S. Department of Veterans Affairs to learn about testing options and medical benefits that may apply.

Previous radiation therapy: On rare occasions, external radiation therapy to treat any form of cancer can lead to the development of soft tissue sarcoma later in life in the treated area. This can occur anywhere from five to 30 years after initial treatment.

Weakened immune system: People with human immunodeficiency virus (HIV) sometimes develop Kaposi sarcoma, a type of soft tissue sarcoma that forms in cells that line blood vessels or lymph vessels.

This rare type of sarcoma is treated differently than other, more common types of soft tissue sarcoma.

Other immune system disorders may also cause an increased risk of soft tissue sarcoma, including lupus, psoriasis or cancers such as chronic lymphocytic leukemia.

Lymphedema: Patients with lymphedema have an increased risk because sarcomas may sometimes form in the same areas. Lymphedema is a type of swelling that develops in the body as a side effect of surgery or radiation therapy. Sometimes people are born with lymphedema.

Is soft tissue sarcoma hereditary?

Some rare, inherited genetic conditions are considered risk factors for soft tissue sarcoma. Speak with the care team if the patient has a family history of sarcomas or any of the conditions listed below.

Familial adenomatous polyposis (FAP): FAP is a genetic condition that causes the growth of adenomatous colon polyps inside the intestinal tract. Gardner syndrome, a variant of FAP, may also form additional tumors outside the gastrointestinal organs.

Retinoblastoma: This eye cancer found in children is linked to defects in the RB1 gene, which may also lead to a higher risk of soft tissue or bone sarcomas. If radiation treatment was used on the retinoblastoma, the risk is increased.

Neurofibromatosis type 1 (von Recklinghausen disease or NF1): This condition causes benign tumors, known as neurofibromas, to form in nerves and other parts of the body. It’s caused by mutations in the NF1 and NF2 genes.

Li-Fraumeni syndrome: This syndrome, linked to mutations in the TP53 gene, causes a higher risk of cancer, particularly brain tumors, leukemia, breast cancer and sarcomas.

Werner syndrome: Children with this syndrome may experience heart problems, cataracts and changes to the skin. It’s due to mutations in the RECQL2 gene.

Gorlin syndrome: Also known as nevoid basal cell carcinoma syndrome (NBCCS), Gorlin syndrome is due to a defect in the PTCH1 gene and may lead to a higher risk of basal cell skin cancers and sarcomas.

Tuberous sclerosis: This disorder is caused by defects in the TSC1 and/or TSC2 gene and may lead to learning difficulties, seizures, kidney problems, benign tumors and sarcomas.

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