Inclusion Criteria:  Histologically confirmed soft-tissue sarcoma of the extremities with an indication for perioperative radiation treatment Resectable or marginally resectable Karnofsky index of ≥ 70% Age ≥ 18 years Carried out patient education and written consent Patient is capable to give informed consent  Exclusion Criteria:  Stage IV (distant metastases) Lymph node metastasis Metal implants that influence treatment planning with ions Previous radiotherapy in the treatment area Desmoid tumors Simultaneous participation in another clinical trial that could influence the results of the study. Active medical implants for which no ion beam irradiation permit exists at the time of treatment (e.g., cardiac pacemaker, defibrillator)