114P Real-world evidence of synovial sarcoma: Prognostic factors and therapeutic approaches from cancer registry data

Background: Conventional (CONV) and extraosseous/post-radiotherapy (EXRD) osteosarcoma are distinct clinical entities with different pathogeneses, but their specific molecular determinants remain undefined.In this study, we compared the genetic backgrounds of these subtypes to identify unique genomic alterations that may underlie distinct oncogenic mechanisms.Methods: We analyzed FFPE samples from the Universities of Pisa and Florence.Informed consent for genetic testing was obtained at diagnosis.DNA was extracted using the DNA FFPE Kit with EZ2 Connect (Qiagen).A custom gene panel was designed based on published WES data.Libraries were prepared with the DNA Prep with Enrichment Kit and run on NextSeq2000 (Illumina).Bioinformatic analysis used optimized pipelines and Pisces to reduce germline variant calls.Odds ratios and chi-squared tests with corrections were calculated as appropriate.