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

Purpose/Objective(s)

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).

Materials/Methods

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.

Results

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.

Conclusion

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.