In-Depth Analysis of Wound Complications Following Preoperative Radiotherapy for Lower Extremity Soft Tissue Sarcoma Patients Colleen Dickie MSc, MRT(T)(MR) Assistant Professor, University of Toronto UHN Princess Margaret Cancer Centre

Acknowledgements Joanne Moseley, BMath Anthony M. Griffin, MSc Amy Parent, MRT(T), BSc, CMD Michael B. Sharpe, PhD Peter C. Ferguson, MD, FRCSC Jay S. Wunder, MD, FRCSC Peter Chung, MD, FRCPC Charles N. Catton, MD, FRCPC Brian O’Sullivan, MD, FRCPC Princess Margaret Cancer Center

Background Phase II preop IG-IMRT trial:  Reduced combined modality morbidities  Minimized dose to uninvolved tissues  Adult LE-STS  Reduced wound complications (WC)  from 43 % (phase III preop arm) to 30.5 % O’Sullivan et al. Cancer, 2013 May 15;119(10):

Background GTV PTV IMRT Trial priority: target coverage Future SF spared if feasible Overlap of flaps with PTV was a significant predictor of WC (p = 0.003) Superficial PTVs WC Baldini et al.:  Tumor proximity to skin surface < 3mm predictor of WC O’Sullivan et al. Cancer, 2013 May 15;119(10): Baldini et al., Ann Surg Oncol, 2013 May;20(5): FLAPS

Objective To retrospectively analyze all the elements of the volume of skin and subcutaneous tissues used to close the resection site (surgical flaps - SF)  Lower extremity STS  Phase II IMRT PMH trial To determine which parameters were associated with WC

Methods / Materials MATLAB / Pinnacle used to quantify:  Mean SF RT dose  SF Volume  Inclusion of fascia  Tumor to skin proximity  GTV and PTV PTV FLAPS GTV PTV FLAPS

Methods / Materials MATLAB used to quantify:  SF Length  SF Width  Variable thickness across length / width of SF  SF and PTV overlap Length Width PTV

Methods / Materials 18 of 59 (30.5%) patients developed WC in IMRT trial  93 % primary closure (55 of 59)  4 non primary- 1 STSG, 1 rotation flap, rotation flap and STSG 8 patients re-planned for tumor growth  5 developed WC (62.5 %)  Analyzed tumor growers separately

Results WCNo WCP value Mean dose - SF33.1 Gy31.7 Gy0.43 Mean volume - SF392.2 cc237.7 cc0.001 SF Width (R - L)2.01 cm1.70 cm0.05 SF Length (S - I)27.5 cm25.0 cm0.07 SF Thickness (A - P)2.02 cm1.76 cm0.24 % SF ≥ 30 Gy65 %61 %0.41 Tumor to skin proximity 2.5 mm2.8 mm0.38 Fasciocutaneous / Subcutaneous SF 7 / 1117 / SF / PTV overlap19 %8 % GTV886.7 cc491.4 cc0.004 PTV cc cc0.0002

8 Growers- RT Dose Map PTV 1 st Plan RePlan PTV Red = prescribed dose Minimal Overlap Increased Overlap Replan- Significantly greater: SF overlap %SF > 30 Gy Shorter tumor to skin (2.2 mm)

Results WCNo WCP valueTumor Growers P value Mean dose - SF33.1 Gy31.7 Gy Gy0.003 Mean volume - SF392.2 cc237.7 cc cc0.59 SF Width (R - L)2.01 cm1.70 cm cm0.99 SF Length (S - I)27.5 cm25.0 cm cm0.35 SF Thickness (A - P)2.02 cm1.76 cm cm0.50 % SF ≥ 30 Gy65 %61 % %0.002 Tumor to skin proximity 2.5 mm2.8 mm mm0.36 Fasciocutaneous / Subcutaneous SF 7 / 1117 / / SF / PTV overlap19 %8 % % GTV886.7 cc491.4 cc cc0.006 PTV cc cc cc0.009

Conclusions WC is reduced when:  92 % of SF is proportionally excluded from PTV Provides volume estimate for IMRT optimization Larger GTV / PTVs were associated with WC Tumor growth may occur at any time during preop IMRT and may:  Increase PTV / SF overlap  Increases SF > 30 Gy  Increase WC rate

Acknowledgements Joanne Moseley, BMath Amy Parent, BSc, MRT(T) Anthony M. Griffin, MSc Michael B. Sharpe, PhD Peter C. Ferguson, MD, FRCSC Jay S. Wunder, MD, FRCSC Robert S. Bell, MD, FRCSC Peter Chung, MD, FRCPC Charles N. Catton, MD, FRCPC Brian O’Sullivan, MD, FRCPC Princess Margaret Cancer Center