Synovial sarcoma in patients under 20 years of age: a multicenter study with a minimum follow-up of 10 years

Synovial sarcoma (SS) is an aggressive soft-tissue tumor noted for late local recurrence and metastasis. This study investigates the long-term outcome of SS in patients of pediatric age and evaluates potential prognostic factors for SS.

We performed a retrospective review of 13 SS cases in patients younger than 20 years at the time of diagnosis who had a minimum follow-up of 10 years. The mean follow-up for living patients (n = 8) was 20.1 years (12.1-27.6) and for nonsurvivors (n = 5) 4.9 years (range: 2.6-9.3). Nine patients had unplanned excisions (69%), of which 6 (67%) were performed prior to their referral. Re-excisions were necessary in all 13 patients. The factors sex, tumor site, tumor size, tumor grade, histological subtype, fusion type, and type of treatment were evaluated for their prognostic value.

Only 2 patients (15%) met the criteria of adequate tumor treatment. Overall, the 5- and 10-year survival rates were 77 and 61%, respectively. The mean time until a local recurrence (n = 5) was 3.2 years (range: 0.7-10.2), while there was a mean time of 2.1 years until the occurrence of late metastases (n = 5; range: 0.8-4.8). A high tumor grade and having a tumor in the trunk were adverse factors in terms of overall, local recurrence-free, and metastasis-free survival. Patients with wide resections or amputations had fewer local recurrences than patients with marginal or intralesional resections.

Inadequate primary excision of SS results in incomplete excision in the majority of cases. The tumor site, size, and histological grade should be considered when determining a risk-adapted treatment for SS, and wide surgical excision is the surgical intervention of choice. While local recurrence and late metastases appear to occur after a shorter time period in pediatric patients than in adults, in view of the tendency for late recurrence and metastasis with SS, follow-up should be at least 10 years.