sentences:  In addition, the synthetic retinoid derivative fenretinide (4-hydroxy(phenyl)retinamide) has been reported to induce high levels of cell death in Ewing's sarcoma cell lines "in vitro" and to delay growth of xenografts in "in vivo" mouse models.In most pediatric cancers including sarcoma, proton beam radiation (also known as proton therapy) delivers an equally effective dose to the tumor with less damage to the surrounding normal tissue compared to photon radiation.Staging attempts to distinguish people with localized from those with metastatic disease.