Outcome of chemotherapy in advanced synovial sarcoma patients: Review of 15 clinical trials from the European Organisation for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group; Setting a new landmark for studies in this entity

Introduction Previous studies in metastatic soft tissue sarcomas (STS) showed that synovial sarcomas tend to have better survival rates and a higher chemosensitivity than other STS subtypes. However, data are derived from relatively small subgroups and statistical significance of these observations is lacking. Larger cohorts are necessary to define and confirm the specific characteristics of this subtype. Patients and methods Patient data were retrieved from 15 European Organisation for Research and Treatment of Cancer advanced first-line STS trials. Patient characteristics, survival and treatment response of synovial sarcoma patients were compared to other STS patients. Univariable and multivariable analyses were performed to evaluate prognostic factors. Results In total, 3330 advanced STS patients were retrieved, of whom 313 had a synovial sarcoma. Synovial sarcoma patients were significantly younger (median 40 versus 52 years), more often had extremity primary tumours and had a better performance status (PS 0: 50.2 versus 43.4%) compared to other STS patients. Additionally, synovial sarcoma patients had a significantly better response to chemotherapy (responders: 27.8 versus 18.8%) and better survival rates (progression free survival [PFS]: 6.3 versus 3.7 months; Overall survival [OS]: 15.0 versus 11.7 months). Age, PS, and presence of metastatic disease were defined as prognostic factors for PFS and OS in the univariable analysis. The last two factors were confirmed in the multivariable analysis for OS. Discussion Advanced synovial sarcomas are a distinct subgroup of STS, with a better response to systemic chemotherapy and longer PFS and OS. These results should be taken into account in the design of future synovial sarcoma specific studies.