Prognostic factors

Extremity primary tumors.

Smaller tumors.

Localized disease.

Response to chemotherapy was correlated with improved survival in one meta-analysis.

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 event-free survival (EFS).[20] In this analysis, local invasiveness conferred an inferior probability of EFS, but surgical margins were not associated with clinical outcome.

In a single-institution retrospective analysis of 111 patients with synovial sarcoma who were younger than 22 years at diagnosis, larger tumor size, greater depth in tissue, greater local invasiveness, and more proximal tumor location were associated with poorer overall survival (OS).[21][Level of evidence C1]

A multicenter analysis included 219 children from various treating centers, including Germany, St. Jude Children's Research Hospital (SJCRH), Instituto Tumori, and MD Anderson Cancer Center. The study reported an estimated 5-year OS rate of 80% and an EFS rate of 72%.[19] 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) group III disease (localized, incompletely resected or with biopsy only) and group IV disease (metastases at diagnosis) had decreased OS. Treatment with radiation therapy was related to improved OS (hazard ratio [HR], 0.4; 95% confidence interval [CI], 0.2–0.7). In patients with IRS group III disease, objective response to chemotherapy (18 of 30 [60%]) correlated with improved survival.

Expression and genomic index prognostic signatures have been studied in synovial sarcoma. Complex genomic profiles, with greater rearrangement of the genome, are more common in adults than in younger patients with synovial sarcoma and are associated with a higher risk of metastasis.[22]

A review of 84 patients with localized synovial sarcoma who had information on fusion status (SS18::SSX) and histological grading found no difference in OS according to these criteria. However, for tumor size at diagnosis, the study showed that patients with tumors between 5 cm and 10 cm had a worse prognosis than those with smaller tumors (P = .02). Patients with tumors larger than 10 cm had an even worse OS (P = .0003).[23][Level of evidence C1]

The German CWS group reviewed 27 evaluable patients younger than 21 years with pulmonary metastases among 296 patients with synovial sarcoma. All patients had metastasis to the lungs. The 5-year EFS rate was 26%, and the OS rate was 30%. The most important prognostic factor at presentation was that the metastases were limited to one lesion in one lung or one lesion in both lungs (a group they termed oligometastatic). Treatment elements associated with superior survival were adequate local therapy of the primary tumor and, if feasible, for the metastases. The use of whole-lung irradiation did not correlate with better outcomes.[24][Level of evidence C1]

The EpSSG designed a genomic index for synovial sarcoma.[25][Level of evidence C2] Genomic index was defined as A2/C, where A is the total number of alterations (segmental gains and losses) and C is the number of involved chromosomes on array comparative genomic hybridization results. In a multivariate analysis of 61 pediatric, adolescent, and young adult patients (aged <25 years), high genomic index was an independent predictor of decreased EFS and OS.

In adults, factors such as International Union Against Cancer/American Joint Committee on Cancer stage III and stage IVA, poor tumor necrosis, truncal location, elevated mitotic rate, older age, and higher histological grade have been associated with a worse prognosis.[26-28]