In a retrospective analysis of synovial sarcoma in children and adolescents who were treated in Germany and Italy, tumor size (>5 cm or ≤5 cm in greatest dimension) was an important predictor of EFS. In this analysis, local invasiveness conferred an inferior probability of EFS, but surgical margins were not associated with clinical outcome. A multicenter analysis of 219 children from various treating centers including Germany, SJCRH, Instituto Tumori, and MD Anderson Cancer Center reported an estimated 5-year OS of 80% and EFS rate of 72%. In this analysis, an interaction between tumor size and invasiveness was observed; in multivariate analysis, patients with large or invasive tumors or with Intergroup Rhabdomyosarcoma Study (IRS) Clinical Group III and IV disease had decreased OS. Treatment with radiation therapy was related to improved OS (hazard ratio, 0.4; 95% confidence interval, 0.2–0.7). In IRS Group III patients, objective response to chemotherapy (18 of 30 [60%]) correlated with improved survival. In adults, factors such as International Union Against Cancer/American Joint Committee on Cancer stage III and stage IVA, tumor necrosis, truncal location, elevated mitotic rate, age, and histologic grade have been associated with a worse prognosis.[129,130,131]
Synovial sarcoma appears to be more sensitive to chemotherapy than many other STSs, and children with synovial sarcoma seem to have a better prognosis when compared with adults.[5,127,131,132,133,134,135,136,137] The most commonly used regimens for the treatment of synovial sarcoma incorporate ifosfamide and doxorubicin.[135,138,139] Response rates to the ifosfamide and doxorubicin regimen are higher than in other nonrhabdomyosarcomatous STSs. A meta-analysis also suggested that response to chemotherapy was correlated with improved survival.
Several treatment centers advocate adjuvant chemotherapy following resection and radiation therapy of synovial sarcoma in children and young adults.[128,136,139,141,142,143] The International Society of Pediatric Oncology-Malignant Mesenchymal Tumors studies showed that select patients (young age, < 5 cm resected tumors) with nonmetastatic synovial sarcoma can have excellent outcome in the absence of radiation, but it is still unclear whether or not that approach obviates an advantage of radiation for local or regional control. A German trial suggested a benefit for adjuvant chemotherapy in children with synovial sarcoma. A meta-analysis also suggested that chemotherapy may provide benefit. However, unequivocal proof of the value of adjuvant chemotherapy from prospective, randomized clinical trials is lacking and the results of COG-ARST0332 are pending. Survival following relapse is poor (30% at 5 years). Factors associated with outcome after relapse include duration of first remission (> or ≤ 18 months) and lack of a second remission.