Neoadjuvant Irradiation of Retroperitoneal Soft Tissue Sarcoma With Ions Retro-Ion

The study is a randomized, open, prospective phase II study. The aim of the study is to evaluate the safety and feasibility of a hypofractionated, accelerated radiation approach based on the incidence of grade 3-5 NCI Common Terminology Criteria for Adverse Events (NCI-CTC-AE ) toxicity and / or termination of the planned therapy for any reason with neoadjuvant radiation with active beam guidance of the retroperitoneal Sarcomas using protons or carbon ions before a subsequent tumor resection.