Rhabdomyosarcoma (RMS) is one of the typical tumors of childhood and adolescence, but it is exceedingly rare in adults. Unfortunately, the treatment success achieved over the years for pediatric RMS has not translated into better cure rates for adults, who continue to have a very poor prognosis (overall survival rates of only 20–40%). To better characterize adult RMS, we performed an analysis of all RMS cases registered on the Surveillance Epidemiology and End Results (SEER) public-access database collected from various geographic areas in the United States from 1973 to 2005.

We analyzed 2600 patients, 1071 adults (> 19 years) and 1529 children (≤19 years). Tumors in adults were more likely to be at an unfavorable site (65% vs. 55%; P< 0.0001) and to have histologies that are unusual during childhood, particularly the pleomorphic subtype (19%) and not otherwise specified (43%). Regional and distant spread was not significantly higher in adults.

Adults had significantly worse outcome than children (5-year overall survival 26.6% and 60.5%, respectively; P< 0.0001). Adults had significantly worse outcome also analyzing subset of patients with similar tumors (i.e. same histotype, same stage). The most significant difference was in localized disease; 5-year overall survival rates were 82.2% and 46.8%, respectively (P < .0001). Multivariate analysis showed that age, histologic subtype, primary site location, stage, treatment with surgery, and treatment with radiation were significant predictors of survival. However, alveolar subtype and unfavorable primary site lost significance when analysis was restricted to adults.

In conclusion, our analysis confirmed that adult RMS was associated with a very poor outcome, especially in contrast to the significant improvements achieved in children treated contemporarily. The outcome for adults is consistently worse regardless of clinical characteristics, suggesting that factors other than an unfavorable clinical presentation might be involved in their unsatisfactory treatment results.

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.