European standard clinical practice recommendations for children and adolescents with non-rhabdomyosarcoma and other rare soft tissue neoplasms: A joint EPSSG and ERN PaedCan project

Non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) are a heterogeneous malignancies with different histopathological characteristics. Distinct molecular findings help to classify NRSTS into subtypes. Further new molecular subtypes give insight into the heterogeneity of these rare tumours. Over the past 25 years, five large international prospective clinical trials have been conducted to improve prognosis for pediatric, adolescent, and young adult patients (< 25 years) with NRSTS and rare soft tissue neoplasms. The overall cure rate is around 70% but varies dramatically between the different entities. New treatment approaches are still needed for some histotypes and for metastatic tumors to improve outcome. The European paediatric soft tissue sarcoma study Group (EpSSG) proposes guidelines developed by an European NRSTS group supported by the European Reference Network on Paediatric Cancer (ERN PaedCan). This consensus summarizes the standard of care, diagnostic work up, multimodal treatment and surveillance recommendations for pediatric, adolescent, and young adult patients with NRSTS and rare soft tissue neoplasms, according to the Consensus Conference Standard Operating Procedure methodology. The unique features of selected histotypes are discussed.