Synovial sarcoma: identification of low and high risk groups

Synovial sarcoma, one of the most common soft tissue sarcomas that occur in adolescents and young adults, is generally viewed and treated as a high grade sarcoma. However, the authors' own experience and some previous studies have indicated that it has a wide spectrum of biologic behavior and that low and high risk subgroups of patients with synovial sarcoma can be identified.

A total of 121 consecutive patients with synovial sarcoma (including 66 males and 55 females ages 9-74 years), treated primarily or secondarily at 2 large referral centers for musculoskeletal tumors, were included in a statistical analysis conducted to identify independent prognostic factors.

There were local recurrences in 38 patients (31%), usually after inadequate primary surgery outside the referral centers; 64 patients (54%) developed metastasis, primarily to the lungs. The estimated 5-, 10-, and 15-year survival rates were 60%, 50%, and 45%, respectively (the mean follow-up for surviving patients was 9.8 years, with a range of 1-30 years). In multivariate analysis, independent risk factors for local recurrence included larger tumor size and primary surgical resection outside the referral center. Independent risk factors for metastasis were older patient age, tumor with poor histologic differentiation, and tumor necrosis. For tumor-related death, the independent risk factors were older patient age, tumor with poor histologic differentiation, and larger tumor size. Local recurrence was associated with a 3.66-fold increased risk of tumor-related death. A low risk group (patient age <25 years, tumor size <5 cm, and no histologic evidence of poorly differentiated tumor) with 88% overall disease free survival was identified, as was a high risk group (patient age > or = 25 years, tumor size > or = 5 cm, and poorly differentiated tumor) with 18% overall disease free survival (P < 0.001).

The identification of low and high risk synovial sarcoma patients indicates that synovial sarcomas are not uniformly high grade tumors. It also indicates that treatment strategies should be modified for these risk groups. Adequate primary surgery is essential to both local control and outcome for synovial sarcoma patients.