Hypofractionated, 3-week, Preoperative Proton or X-ray Radiotherapy for Patients With Localized Soft Tissue Sarcoma

The purpose of the study is to investigate whether a personalized selection of patients with localized soft tissue sarcoma for preoperative proton radiation therapy can reduce long-term radiation side effects without increasing surgical complications or reducing the effectiveness of the treatment. Two radiation plans will be created for each patient-one for protons and one for photons-and through a national meeting, we will determine which type of radiation therapy each patient will receive. The radiation dose will be the same for both photons and protons. The primary endpoint is surgical complications 120 days after surgery. Secondary endpoints include overall survival, local recurrence-free survival, disease-free survival, side effects, and quality of life. Furthermore, the study will investigate biomarkers that may predict response to radiation therapy, including changes in the tumor's genetic material (DNA), measurement of various molecules in the bloodstream, and the tumor's appearance on MRI scans. The study will be conducted in Norway, with a planned inclusion of 110 patients.