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 can be modified, such as lifestyle or environmental risk factors, and 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 a person 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 uterine sarcoma include: 

• age – most women who are diagnosed with uterine sarcoma are over 50 years old 
• obesity – extra fatty tissue produces extra estrogen, which can increase the risk of uterine sarcoma 
• past treatment with radiotherapy to the pelvis 
• treatment with tamoxifen for breast cancer, especially for a long time (5 years or more) 
• family history of Lynch syndrome, also called hereditary non-polyposis colorectal cancer (HNPCC), which is also linked to an increased risk of colon, kidney, bladder and ovarian cancer^[1] 
• a type of eye cancer called retinoblastoma that was caused by having an abnormal RB gene.^[2]