Pediatric-type sarcomas in adult patients: Age is an independent prognostic factor in IRS group I/II

Abstract

9552 Backgrounds: A number of pediatric sarcomas occur in adults, including Ewing’s sarcoma (EWS)/primitive neuroectodermal tumor (PNET) and rhabdomyosarcoma (RMS). However, these are rare in adult patients (pts) and differ from typical adult sarcomas in that they are generally considered as systemic disease. There is debate as to whether adults do worse than pediatric pts with the same stage of disease. This study was performed to investigate whether various clinical parameters such as tumor size, primary site, age at diagnosis and response to chemotherapy predict the outcome. Methods: 74 consecutive cases of previously untreated pts over 18 years who were diagnosed with EWS/PNET, RMS, and desmoplastic small round cell tumor (SRCT) between 1995 and 2005, were identified from the database at the Samsung Medical Center. Among them, 64 pts were reviewed retrospectively and 10 pts who were lost to follow up were excluded. All pts were treated by a multimodality therapeutic approach, including surgery, chemotherapy, and radiotherapy, based on the ongoing protocols at the time of diagnosis. Results: The median age of the patients was 28 years (range, 18 - 74 years) and the majority (62.5%) of patients was male. There were 35 (54.6%) cases of EWS/PNET, 25 (39.1%) of RMS and 4 (6.3%) of desmoplastic SRCT. 29 pts (45.3%) had metastatic disease and 42 pts (65.6%) were Intergroup RMS Study (IRS) groups III/IV at diagnosis. Median overall survival was 41.5 months (95% CI, 16.1–66.9 months) and 5 years-survival rates was 38.7% (95% CI, 26.7–50.6%) in all pts. In univariate analysis, age (p=0.015), IRS group (p=0.0007) and tumor size (p=0.044) were correlated with better survival. However, multivariate analysis showed that independent variables for better survival were age (p=0.017) and IRS group (p=0.016). In subset analysis, significant statistical correlation between age and overall survival was observed in pts with IRS group I/II. Notably, pts younger than 30 years showed favorable outcome. Conclusions: In this study, age at diagnosis and IRS group reflecting tumor burden were important prognostic factors. Therefore, it is necessary that adult pts with pediatric sarcomas should be included in pediatric protocols, whenever feasible, to provide proper management for the rare disease. No significant financial relationships to disclose.