High Dose (54 Gy) Pre-Operative Helical Tomotherapy for Retroperitoneal Liposarcoma

Abstract

<h3>Purpose/Objective(s)</h3> To evaluate efficacy and feasibility of high-dose intensity-modulated radiotherapy (RT) with pre-operative helical tomotherapy, delivering 54 Gy/30 fractions in patients with retroperitoneal liposarcomas (RPLS). <h3>Materials/Methods</h3> Patients with operable, biopsy-proven, RPLS were included in this phase II multicenter study. Surgery was planned 4 to 8 weeks following RT. The primary objectives were to analyze cumulative incidence of loco-regional relapse (LRR), overall survival (OS) and toxicities, graded according to CTCAE V3.0. <h3>Results</h3> From April 2009 to September 2013, 48 patients were included. Median age was 63 years (range, 36-82 years). Performance status was ≤ 2 except for one patient. Histological types were: 20 well differentiated (WDLS) and 28 dedifferentiated liposarcomas. Median clinical target volume (CTV) was 2570 cc (range, 0-8734 cc). The radio-surgical schedule was completed as planned in all patients apart from one. A monobloc wide excision was achieved for all patients. Surgical margins were R0 (16; 34%), R1 (28; 60%), R2 (2; 4%) or missing (1; 2%). With a median follow-up of 5.5 years, cumulative incidence of LRR at 3 years and 5 years was 16.9% [95%CI, 7.9-28.8] and 25.6% [95%CI, 14.2-38.6], respectively. The 3- and 5-year OS was 80.6% [95%CI, 66.0-89.4] and 73.9% [95%CI, 58.7-84.3], respectively. During RT, the most common grade 3-4 adverse events were hematological (N=20; 41.6%) and general (N=3; 6.3%). After surgery and during follow-up, 17 patients (35.4%) presented a grade 3-4 toxicity. Two patients (4.1%) died due to a duodenal toxicity. Nine second cancers were observed. <h3>Conclusion</h3> This phase II trial confirms the feasibility of preoperative high-dose RT in RPLS patients. Although efficacy of this approach is supported by adequate local control and OS data, toxicity within the first 6 months was non-negligible. Furthermore, due to low number of events, the relevance of a pre-operative RT for WDLS remains questionable.