Primary Synovial Sarcoma of the Extremities Benefits From Perioperative Radiation and Chemotherapy.

OBJECTIVES: Synovial sarcoma (SS) mostly arises in the extremities, yet data focused exclusively on primary extremity tumors remain limited. Therefore, we evaluated survival outcomes in patients with localized extremity SS treated at a large sarcoma referral center. METHODS: A retrospective chart review of patients diagnosed with primary extremity SS between 2000 and 2020 with localized disease was conducted. Overall survival (OS), local recurrence-free survival (LRFS), and metastasis-free survival (MFS) were evaluated. RESULTS: The study included 287 patients (median age: 35 y; follow-up: 5.3 y). Most tumors arose in the lower extremity (75%), and the median tumor size was 6 cm (range: 0.4 to 24). The median OS was 14 years, with a 10-year OS of 57%. Ten-year LRFS was 76%, and 10-year MFS was 51%. Tumors ≥5 cm (aHR: 2.06, 95% CI: 1.12-3.79), and the poorly differentiated subtype (aHR: 1.93, 95% CI: 1.01-3.69) were associated with inferior OS. For LRFS, positive/unknown margins were strongly associated with elevated local-recurrence risk (aHR: 4.09, 95% CI: 2.30-7.28), whereas perioperative radiation therapy significantly improved LRFS (aHR: 0.38, 95% CI: 0.22-0.68). For MFS, in a subgroup of patients with tumors ≥4 cm, perioperative chemotherapy was independently associated with improved MFS (aHR: 0.54, 95% CI: 0.34-0.86). CONCLUSIONS: Outcomes in extremity SS are driven by tumor size, subtype, and margin status. Perioperative radiation is recommended as it is associated with superior local control, and perioperative chemotherapy is highly recommended, particularly in patients with a tumor size of ≥4 cm, as it is associated with improved MFS.