Prognostic implication of SYT-SSX fusion type in synovial sarcoma: A multi-institutional retrospective analysis in Japan

Synovial Sarcoma: A Clinical Review

Synovial sarcomas (SS) represent a unique subset of soft tissue sarcomas (STS) and account for 5–10% of all STS. Synovial sarcoma differs from other STS by the relatively young age at diagnosis and clinical presentation. Synovial sarcomas have unique genomic characteristics and are driven by a pathognomonic t(X;18) chromosomal translocation and subsequent formation of the SS18:SSX fusion oncogenes. Similar to other STS, diagnosis can be obtained from a combination of history, physical examination, magnetic resonance imaging, biopsy and subsequent pathology, immunohistochemistry and molecular analysis. Increasing size, age and tumor grade have been demonstrated to be negative predictive factors for both local disease recurrence and metastasis. Wide surgical excision remains the standard of care for definitive treatment with adjuvant radiation utilized for larger and deeper lesions. There remains controversy surrounding the role of chemotherapy in the treatment of SS and there appears to be survival benefit in certain populations. As the understanding of the molecular and immunologic characteristics of SS evolve, several potential systematic therapies have been proposed.

Systemic Anti-Cancer Therapy in Synovial Sarcoma: A Systematic Review

Synovial sarcoma (SS) is an aggressive malignancy which accounts for approximately 5–10% of all soft-tissue sarcomas. SS has pathologic and genomic characteristics that define it as a distinct subtype of soft tissue sarcoma (STS). STS subtypes continue to be recognized as distinct entities with specific characteristics, including differential chemo-sensitivity. The objective of this study was to conduct a descriptive review of current data on survival outcomes of systemic anti-cancer therapy specific to SS. A systematic literature review was conducted, using a custom search strategy to search EMBASE, Medline and CENTRAL for clinical trials and observational studies reporting overall survival (OS), progression-free survival (PFS) and/or response for cohorts of at least 50 SS patients. We identified 28 studies meeting these criteria, 25 of which were retrospective studies. Only three prospective studies were identified. Survival reports varied widely between studies based on the population, in particular on the disease stage, and reporting was heterogeneous in terms of the time points reported on. For patients with localized disease, reports of five-year PFS ranged from 26% to 80.7% and five-year OS from 40% to 90.7%, whereas five-year OS for patients with metastatic disease was very low at around 10%; and in one case, 0% was reported. Only four of the included publications reported outcomes by type of systemic anti-cancer therapy received. Our study draws attention to the fact that additional prospective studies to better define the most appropriate treatment for SS in all stages and lines of therapy are still needed.

A synovial sarcoma-specific preoperative nomogram supports a survival benefit to ifosfamide-based chemotherapy and improves risk stratification for patients

PURPOSE

To identify prognostic factors related to outcome in 255 patients with synovial sarcoma and to construct a preoperative nomogram to predict the risk of disease-specific death.

DESIGN

Between July 1982 and June 2006, 301 patients underwent treatment at our institution for primary synovial sarcoma of all anatomic sites and 255 patients with localized disease at presentation were resected with curative intent. Data were collected prospectively and analyzed retrospectively.

RESULTS

Five-, 10-, and 15-year disease-specific survival (DSS) was 72%, 60%, and 53%, respectively. Multivariate analysis revealed size and primary tumor site as the only independent adverse predictors of disease-specific death. A nomogram based on preoperative data for surgical patients not receiving anthracycline-ifosfamide (AI) chemotherapy (n = 196) estimates 3- and 5-year DSS with a concordance index of 77.3%. For the first 3 years following diagnosis, the observed DSS for patients treated with AI chemotherapy (n = 59) was greater than that predicted by the preoperative nomogram based on patients not receiving AI chemotherapy. SYT-SSX fusion transcript data were available for 132 patients. Multivariate analysis of this subset showed that SYT-SSX1 fusion type was predictive of early, but not late, distant recurrence.

CONCLUSION

Size and location govern prognosis in primary synovial sarcoma resected with curative intent. A nomogram based on preoperative variables provides individualized patient survival estimates and shows an early survival benefit to chemotherapy that may dissipate over time. This nomogram may improve decision-making with regards to selecting patients most likely to benefit from neoadjuvant/adjuvant chemotherapy.