Synovial sarcoma (SS) is a typical soft tissue sarcoma subtype crosswise between the pediatric and the adult age groups. No published data describes a different biology of SS when arising in adults as opposed to children, but different therapeutic strategies have been developed for pediatric and adult oncology protocols dealing with SS (in particular concerning the use of systemic therapy) and different overall outcomes have been reported by pediatric and adult groups.

To better characterize the clinical features and outcomes of SS across the different age groups, we performed an analysis of all SS cases registered on the Surveillance, Epidemiology, and End Results (SEER) public-access database collected from various geographic areas in the United States, from 1983 to 2005.

We analysed 1268 cases, 213 children/adolescents (≤18 years) and 1,055 adults.

No major differences in stage distribution (localized, regional and distant stage) and clinical features were observed comparing the two age-groups, though a quite different pattern was recorded just for the small group of patients younger than 10 years (2.5% of cases, more extremity primaries, smaller tumors, mostly localized). The estimated 5-year cancer-specific survival was 83% for children/adolescents and 62% for adults (p< 0.001). Female sex, non-black race, tumors located in the extremities, localized tumors and tumors < 5 cm in size were associated with better survival. In multivariate analysis, adult patients had significantly higher mortality rates than children after adjusting for other variables.

In conclusion, our analysis showed that children/ adolescents and adults with SS have a similar clinical presentation but a dissimilar outcome, suggesting that factors other than unfavorable clinical features might be involved in the unsatisfactory outcome of adult SS patients. It remains to be ascertained whether this difference may be related to biological variables or to historically-different treatment approach adopted in pediatric versus adult patients.