Soft tissue sarcomas (cancer) start from cells similar to those that make up the tissue which lines the joints of the body, the synovium. But synovial sarcoma cells do not actually start in the synovium.
The usual treatment for a synovial sarcoma is surgery. Sometimes this is followed by radiotherapy, to reduce the chance of the cancer coming back. Occasionally a synovial sarcoma is too large or attached to surrounding body tissues to remove with an operation. In this situation, radiotherapy or chemotherapy may be given to try to shrink the sarcoma and make an operation possible.