Hypofractionated Radiotherapy in Locally Advanced Myxoid Liposarcomas of Extremities or Trunk Wall: Results of a Single Arm Prospective Clinical Trial

Abstract

Preoperative hypofractionated radiotherapy 5x5 Gy for five consecutive days, and then immediate surgery in patients with locally advanced soft tissue sarcomas (STS) showed a good local control rate and treatment tolerance. Myxoid liposarcoma (MLPS) is highly radiosensitive as compared with other STS, thus a longer gap between the end of RT and surgery may increase the local efficacy and allow to obtain better pathological response rate. The main objective of the study was to assess the safety of 5x5 Gy hypofractionated preoperative RT with prolonged gap (6-8 weeks) to surgery in patients with locally advanced primary MLPS. In this single-arm prospective clinical trial. Patients with locally advanced MLPS underwent preoperative 5x5 Gy RT with 6-8 weeks gap between RT end and surgery from April 2015 to January 2019. The primary endpoint of the study was the rate of perioperative wound healing complications. The secondary endpoints were the pathological response according to the European Organization for Research and Treatment of Cancer - Soft Tissue and Bone Sarcoma Group recommendations (EORTC-STSBG) and local control rate at 5 years. From April 2015 until February 2019 29 patients with primary MLPS finished the whole planned protocol treatment. All of the patients had the tumors located in the lower limb. The median tumor size was 16 cm. The median follow-up time was 13 months. Perioperative wound complications occurred in 9 patients (31%). 6 patients (21%) required medical intervention (antibiotics or wound revision, grade 2 or higher according to Common Terminology Criteria for Adverse Events version 4.03). These results are similar (32.4%) to our historical controls of 272 patients with advanced STS who were treated with 5x5 Gy RT and immediate surgery. R0 margins were achieved in all but two patients (7%) who had R1 resection margin. None of the patients had local recurrence and four patients (14%) developed distant metastases at the moment of analysis (February 2019). The pathological response category according to the EORTC-STSBG recommendations were B (3.5%), C (20.7%), D (34.5%) and E (41.38%). Preoperative hypofractionated RT with the prolonged gap between the RT and surgery is a reasonable approach to MLPS treatment providing a low rate of perioperative complications and good local control.