A risk factor  is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices.
Most sarcomas do not have known causes. The following factors can raise a person’s risk of developing sarcoma:
Previous radiation therapy. People who have been treated with radiation therapy for a previous cancer have a slightly increased risk of later developing sarcoma.
Genetics. People with certain inherited diseases, such as von Recklinghausen’s disease (neurofibromatosis ), Gardner syndrome , Werner syndrome , tuberous sclerosis , nevoid basal cell carcinoma syndrome , Li-Fraumeni syndrome , or retinoblastoma  have a higher risk of sarcoma.
Chemicals. Workplace exposure to vinyl chloride monomer (used in making some types of plastics) or to dioxin may increase the risk of sarcoma. However, most sarcoma is not known to be associated with specific environmental hazards.