A risk factor is any factor that is associated with increasing someone’s chances of developing a certain condition, such as cancer. Some risk factors are modifiable, such as lifestyle or environmental risk factors. Others cannot be modified, such as inherited factors or whether someone in the family has had cancer. 

Having 1 or more risk factors does not mean that you will develop cancer. Many people have at least 1 risk factor but will never develop cancer, while others with cancer may have had no known risk factors. 

Even if a person with cancer has a risk factor, it is usually hard to know how much that risk factor contributed to the development of their disease. 

Risk factors for soft tissue sarcoma include: 

• certain inherited disorders – retinoblastoma, neurofibromatosis (von Recklinghausen disease), tuberous sclerosis (Bourneville disease), familial adenomatous polyposis (Gardner syndrome), Li–Fraumeni syndrome, Werner syndrome, nevoid basal cell carcinoma syndrome (Gorlin syndrome) 
• previous radiation therapy for other cancers, such as breast cancer or lymphoma 
• exposure to some chemicals (thorium dioxide, vinyl chloride, arsenic) 
• having lymphoedema (swelling) in the arms or legs for a long time – lymphoedema can occur when lymph nodes have been removed or damaged by radiation therapy. 

Risk factors for bone sarcoma include: 

• certain inherited disorders – Bloom syndrome, Diamond–Blackfan anaemia, retinoblastoma, Li–Fraumeni syndrome, Paget disease, Rothmund–Thomson syndrome, Werner syndrome, hereditary multiple osteochondromas (benign bone tumours) 
• previous radiation therapy 
• previous treatment with anticancer medicines called alkylating (JS1) agents. 

Studies of children with Ewing tumours have not found any links to radiation, chemicals, other environmental exposures or inherited disorders. 

Most gastrointestinal stromal tumours (GISTs) have no clear cause and are not inherited. However, inherited disorders increase the risk in some families. These disorders include primary familial GIST syndrome, neurofibromatosis (von Recklinghausen disease) and Carney–Stratakis syndrome. 

Lifestyle factors such as smoking, diet and exercise are not risk factors for sarcoma. 

If you have any of these risk factors or are concerned about your risk of sarcoma, please see your doctor.