Dose Reduction of Preoperative Radiotherapy in Myxoid Liposarcoma: The Phase 2 DOREMY Nonrandomized Clinical Trial.

Importance: Prospective data from 2 phase 2 trials showed favorable wound complication rates and promising local control after a reduced preoperative radiotherapy dose for myxoid liposarcoma (MLS). However, long-term follow-up data are currently lacking. Objective: To determine the efficacy and toxicity profile of a reduced preoperative radiotherapy dose in patients with MLS with long-term follow-up. Design, Setting, and Participants: The Dose Reduction of Preoperative Radiotherapy in Myxoid Liposarcoma (DOREMY) trial is a prospective, single-group, phase 2 nonrandomized clinical trial conducted in 9 tertiary sarcoma centers in Europe and the US. Eligible patients were adults with biopsy-proven and translocation-confirmed localized MLS of the trunk or extremity who were enrolled from November 24, 2010, to May 14, 2020. Data were analyzed from January to December 2025. Intervention: Preoperative radiotherapy to a reduced dose of 36 Gy in once-daily 2-Gy fractions followed by resection. Main Outcomes and Measures: Long-term local recurrence-free survival, progression-free survival, disease-specific survival, overall survival, and late toxic effects. Results: Ninety patients (mean [SD] age, 47 [13.1] years; 50 [56%] male) were included and followed up for a median (IQR) of 66.4 (48.8-87.5) months. Preoperative radiotherapy was delivered according to protocol in all patients. Surgery was not performed in 3 patients (3%) due to intercurrent metastatic disease. Local recurrence-free survival, progression-free survival, disease-specific survival, and overall survival rates at 5 years were 97.4% (95% CI, 93.9%-100%), 81.0% (95% CI, 72.6%-89.4%), 89.5% (95% CI, 82.6%-96.4%), and 88.5% (95% CI, 81.2%-95.8%), respectively. In total, 18 patients (21%) experienced a wound complication, and 14 (16%) required intervention. Any grade 2 or grade 3 late toxic effects were seen among 13 patients (15%) and 3 patients (3%), respectively. Conclusions and relevance: This long-term analysis of the DOREMY nonrandomized clinical trial demonstrated excellent local control and a favorable toxicity profile following dose reduction of preoperative radiotherapy in patients with MLS. These compelling phase 2 findings support adoption of this regimen as an appropriate treatment option through shared decision-making with the patient, given the impracticality of conducting a phase 3 trial for a rare cancer. Trial Registration: ClinicalTrials.gov Identifier: NCT02106312.