Retroperitoneal sarcomas (RPS) account for approximately 15 per cent of soft tissue sarcomas (STS).1While surgery is the mainstay of treatment, due to anatomical location,complete resection in RPS is challenging. Macroscopic complete (R0+R1) resection, a predictor of overall survival (OS), is only achieved in up to 70-80 per cent of cases.2,3 Howeverdespite macroscopic complete resection, local recurrence is common and, unlike in extremity STS, cancer mortality in RPS is more commonly related to locoregional recurrence rather than metastatic spread.2,4 The role of radiotherapy (RT) in the...

Two female patients with RPS were treated to 60Gy in 30-33 fractions, using single-phase VMAT technique. Patient 1 was diagnosed with a 200mm right-sided primary dedifferentiated retroperitoneal liposarcoma afterpresenting withback pain.Following CT staging to exclude metastatic disease, she underwent laparotomy with resection of a right-sided retroperitoneal sarcoma and right nephrectomy. Histology demonstrated an R1 resection with differentiated liposarcomapresent at the radial, posterior and anterior margins. Well-differentiated liposarcoma was seen in retrocaval adipose tissue. Patient 2 was diagnosed with an inoperable inferior vena cava leiomyosarcoma after...

Using VMAT technique, a dose of 60 Gy was achieved for both patients with minimal compromise of PTV coverage, while keeping organs at risk within departmental dose constraints. Patient 1: GTV was 150cm3 and correlating PTV was 677cm3. The95% isodose line covered 79% of the PTV. PTV coverage was deliberately reduced near bowel to keep dose to 300cm3 bowel volume below 45Gy (V45 achieved 290cm3).The solitary left kidney received a mean dose of 3.95Gy. Patient 2: GTV was 106.3 cm3and correlatingPTV was 320.2cm3. The95% isodose...

Our approach suggests that a VMAT technique can be used to safely deliver a dose of at least 60 Gy in patients with retroperitoneal sarcoma, with minimal acute toxicity. Results of Phase 3 studies such as the STRASS study are awaited to evaluate survival benefits and risk of late toxicities.

A. Xu-Holland, E. Myburgh, W Donaldson, F. Saran. Department of Radiation Oncology, Auckland City Hospital, Private Bag 92 024, Auckland 1142, New Zealand. Mail to: [email protected] I. Cranshaw. Deparment of General Surgery, Auckland City Hospital, Auckland, New Zealand.

Brennan MF, Antonescu CR, Moraco N, Singer S. Lessons learned from the study of 10,000 patients with soft tissue sarcoma. Annals of surgery. 2014 Sep;260(3):416. Lewis JJ, Leung D, Woodruff JM, Brennan MF. Retroperitoneal soft-tissue sarcoma: analysis of 500 patients treated and followed at a single institution. Annals of surgery. 1998 Sep;228(3):355. Keung EZ, Hornick JL, Bertagnolli MM, Baldini EH, Raut CP. Predictors of outcomes in patients with primary retroperitoneal dedifferentiated liposarcoma undergoing surgery. Journal of the American College of Surgeons. 2014 Feb 1;218(2):206-17. Heslin...