10529 Background: A genomic index (GI) tool using array comparative genomic hybridization (aCGH) on tumor cells has recently been developed, and shown a high prognostic value in adult soft tissue sarcomas. GI correlates with genomic instability, and has emerged as independent prognostic factor associated with the risk of metastases developing in synovial sarcoma (SS). The aim, therefore, was to assess GI in pediatric patients with SS, to assess its value as a prognostic factor and its role in risk stratification. Methods: All pediatric/adolescent/young adults’ (<25 years) with localized SS prospectively included in the European EpSSG-NRSTS05 protocol with a contributive aCGH were selected. Tumors had a central pathological review or harbored the specific fusion transcript (SYT-SSX). Definition of GI was A2/C, where A is the total number of alterations (segmental gains and losses) and C is the number of involved chromosomes on aCGH results. GI1 group corresponds to cases with no or few alterations (flat profile, GI≤1) and GI2 group cases with many alterations (complex CGH profile; GI>1). Results: A total of 48 patient’s samples were available. The median age of the cohort was 13 years (range: 4-24). Patients received surgery only (19%), with adjuvant therapy (17%) or perioperative therapy (64%). GI1 group corresponded to 54.2%, and GI2 to 45.8%. After a median follow up of 58 months (range: 0.1-107), 10 tumor events occurred and 5 patients died. Patients with high GI have more axial (P<0.01), invasive (P=0.04) and higher therapeutic risk groups’ tumors (unresectable/axial tumors; P<0.015). Respectively for GI1 vs. GI2 groups, 5-year event free survival (EFS) rates were 91.8±5.6% vs. 58.9±11.2% (P<0.0084) and 5Y-Metastatic Free Survival 91.8±5.5% vs. 68.6±10.6% (P=0.055). In multivariate analysis, GI adjusted for IRS groups, site and tumor size remains prognostic for EFS (P<0.025). Conclusions: Although tumor events were rare for SS in NRSTS 2005, high GI selected patients with high risk tumor features and predicted a poorer outcome. GI may explain aggressive behavior of some pediatric SS. Founding sources: “Enfant-et-santé/SFCE,” “Info sarcome,” and “La ligue contre le cancer.”
Nuclear immunoreaction of p53 protein in soft tissue sarcomas. A possible prognostic factor
