Soft tissues such as muscles, blood vessels, fat, tendons, and lining of the joints connect, support, and surround other body structures. Cancers that originate in these soft tissues are known as soft tissue sarcomas. There are more than 50 types of soft tissue sarcomas, including Kaposi sarcoma, Rhabdomyosarcoma, alveolar soft part sarcoma, adult fibrosarcoma, clear cell sarcoma, liposarcomas, and synovial sarcoma. Common types of soft tissue sarcomas include leiomyosarcoma, abdominal sarcoma, liposarcoma, and undifferentiated pleomorphic sarcoma. According to the American Cancer Society, more than 11,400 new cases of soft tissue sarcoma were diagnosed in the U.S. in 2014. The causes of soft tissue sarcoma are difficult to determine; however, exposure to certain chemicals such as phenoxyacetic herbicides and dioxins; previous exposure to radiotherapy; old age; and certain genetic conditions are anticipated to increase the risk of soft tissue sarcoma. Diagnostic methods used to detect soft tissue sarcoma include PET scan, biopsy, CT scan, and X-ray imaging.