Synovial sarcoma prognostic factors and patterns of failure.

From 1970 to 1999, 44 patients with synovial sarcoma were seen at the University of Iowa. Tumor size was > or = 5 cm in 24 (55%). Histologic classification was biphasic in 26 (59%) and monophasic in 18 (41%). Seven patients (16%) had distant metastasis at initial presentation. For the 37 nonmetastatic patients, local treatment consisted of wide local excision in 29 and amputation in 8; chemotherapy was administered to 10. For the 29 who underwent wide local excision, microscopic resection margins were negative in 18 and positive in 11; 19 received postoperative radiotherapy. The 5-, 10-, and 20-year overall survival rates for the nonmetastatic group were 65.6%, 45.5%, and 37.8%. On multivariate analysis using age as a continuous covariate, younger age (p = 0.028), biphasic histology (p = 0.014), and extremity sites treated with limb-sparing surgery (p = 0.001) were found to be predictors of a better overall survival. No local failures were found after 5 years from initial diagnosis. On multivariate analysis, tumor location at an extremity site was the only variable marginally found to have a better local control (p = 0.065). Of the 19 patients who developed distant metastasis, 5 (26%) failed >5 years and 2 (11%) failed >15 years of follow-up. Younger age, biphasic histology, and extremity sites were found to have a better survival outcome. Late distant relapses can occur with synovial sarcoma.