Risk factors for soft tissue sarcoma
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. But sometimes soft tissue sarcoma develops in people who don’t have any of the risk factors described below.
The following are risk factors for soft tissue sarcoma. Most of the known risk factors are not modifiable. This means that you can’t change them. Until we learn more about these risk factors, there are no specific ways you can reduce your risk.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
Significant evidence shows that there is no link between injury or trauma and increased soft tissue sarcoma risk.
Known risk factors
There is convincing evidence that the following factors increase your risk for soft tissue sarcoma.
People who receive radiation therapy as treatment for another cancer have a higher risk of developing soft tissue sarcoma. This is particularly true for people who received radiation therapy for Hodgkin lymphoma, non-Hodgkin lymphoma or breast cancer. The soft tissue sarcoma often develops in the area of the body that was treated with radiation. The average time between radiation exposure and a diagnosis of sarcoma is 10 years.
Less than 5% of sarcomas are caused by radiation therapy. The benefit of using radiation therapy to treat cancer outweighs the higher risk of developing sarcoma.
The following rare inherited conditions increase the risk of developing soft tissue sarcoma.
Retinoblastoma is a cancerous tumour that develops in the light-sensitive lining of the eye (called the retina). It occurs mostly in children.
The hereditary form of retinoblastoma is caused by a mutation in the RB1 gene.
Werner syndrome is a very rare condition caused by a mutation in the WRN gene. It causes people to age very quickly and prematurely after puberty.
Li-Fraumeni syndrome usually involves a mutation of the TP53 gene or the CHEK2 gene. It is associated with an increased risk of developing several types of cancer, including soft tissue sarcoma.
Neurofibromatosis type 1
Neurofibromatosis is a condition that causes tumours to form in nerve tissues in and under the skin. It is caused by a mutation in the NF1 gene. People with neurofibromatosis type 1 (also known as von Recklinghausen disease) have a higher risk of developing certain cancers, including soft tissue sarcoma.
Gardner syndrome is a rare condition caused by a mutation in the APC gene. It causes large numbers of polyps in the colon, along with tumours in the bone and soft tissues.
Basal cell nevus syndrome
Basal cell nevus syndrome is also called Gorlin syndrome or nevoid basal cell carcinoma syndrome. It is a rare disorder caused by a mutation in a gene that suppresses tumours, known as the patched gene (PTCH1). This syndrome causes different problems with the skin, eyes, nervous system, endocrine glands and jawbone.
People who have had another type of cancer have a higher risk of developing soft tissue sarcoma. This increased risk may be due to common risk factors, such as genetics or cancer treatments.
Lymphedema is a buildup of fluid in body tissues. Long-term, or chronic, lymphedema can cause lymphangiosarcoma (also called Stewart-Treves syndrome). This is a rare type of soft tissue sarcoma that develops in lymph vessels.
The following viral infections may increase the risk of developing soft tissue sarcoma.
Kaposi sarcoma herpes virus (KSHV)
Kaposi sarcoma herpes virus (KSHV) is also called human herpes virus 8 (HHV-8) or Kaposi sarcoma-associated herpes virus. Doctors believe that this virus causes a rare type of sarcoma called Kaposi sarcoma (KS). This virus is found in the lesions of all people with AIDS-related KS.
Human immunodeficiency virus (HIV)
In addition to having a higher risk of developing KS, people with HIV have a higher risk of developing soft tissue sarcoma.
Vinyl chloride is used in the plastics industry to make polyvinyl chloride (PVC), which is used in many products. Occupational exposure to vinyl chloride increases the risk of developing both hepatocellular carcinoma and angiosarcoma of the liver.
Thorium dioxide (Thorotrast) is a radioactive solution that was used as a contrast medium in the 1950s to improve x-ray images of the blood vessels and arteries, nasal passages and sinus cavities. Thorium dioxide was injected into a vein and collected in the liver, spleen and bone marrow.
People who were exposed to thorium dioxide have a greater risk of developing angiosarcoma of the liver. Higher doses of thorium dioxide increase the risk. The cancer may develop as many as 45 years after exposure.
The following factors have been linked with soft tissue sarcoma, but there is not enough evidence to show they are known risk factors. Further study is needed to clarify the role of these factors for soft tissue sarcoma.
Certain chemotherapy drugs, particularly alkylating agents, may be linked with the development of soft tissue sarcoma. Soft tissue sarcoma can develop many years after treatment with chemotherapy. The benefit of using chemotherapy to treat cancer outweighs the increased risk of developing sarcoma.
Exposure to dioxin
Some studies suggest that exposure to dioxin increases the risk of developing soft tissue sarcoma. People can be exposed to dioxin by working in certain industries or when it is released into the air from waste incinerators.
Unknown risk factors
It isn’t known whether or not exposure to herbicides is linked with soft tissue sarcoma. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if exposure to herbicides is a risk factor for soft tissue sarcoma.
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
Thanks to the incredible progress in retinoblastoma research made possible by Canadian Cancer Society funding, my son won’t have to go through what I did.
How can you stop cancer before it starts?
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