Factors influencing survival in metastatic synovial sarcoma: importance of patterns of metastases and the first-line chemotherapy regimen.

Metastatic synovial sarcoma (SS) is associated with poor prognosis. Nevertheless, data addressing prognostic factors for patients with metastatic disease are very limited. We identified patients with SS who presented with or developed metastases at our institution from January 2000 to October 2012. Potential demographic and disease-related factors were analyzed for possible influence on survival. A second analysis for patients who received chemotherapy was undertaken to assess efficacy of first-line regimens. Thirty-three patients with metastatic SS were included in this analysis. The following factors were associated with inferior overall survival (OS); age >30 years, presence of extra-pulmonary metastases, lymph node (LN) involvement, presence of uncontrolled primary site, and treatment not including pulmonary metastasectomy. Multivariate analysis identified LN metastases (HR 6.06, 95% CI 1.18-31) and extra-pulmonary metastases (HR 4.06, 95% CI 1.22-13.57) as the only independent factors associated with inferior OS. Assessment of efficacy of first-line chemotherapy showed superiority in progression-free survival (PFS) for ifosfamide-containing regimens versus non-ifosfamide-containing regimens (median PFS of 8.3 and 2.5 months, respectively, p = 0.002). No such significant difference in PFS was detected for comparison between doxorubicin- and non-doxorubicin-containing regimens (p = 0.45). The current study highlights that the pattern of metastases at first detection of metastatic disease is an important determinant of survival. Future studies evaluating therapeutic strategies for metastatic SS should address the comparability of those factors among study arms. In addition, our results suggest that high-dose ifosfamide should be an integral component of first-line chemotherapy regimen.