Princess Margaret Cancer Center, University Health Network Toronto, ON
N. Wattakiyanon1,2, A. Griffin3, Z. Liu4, C. Catton1,5, D. B. Shultz1,5, P. Wong1,6, D. G. Kirsch1,5, H. M. Othman1, P. Ferguson3,5, J. Wunder3,5, K. Tsoi3,5, and P. Chung1,5; 1Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada, 2Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, 3Mount Sinai Hospital, Toronto, ON, Canada, 4Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada, 5University of Toronto, Toronto, ON, Canada, 6Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, ON, Canada
Purpose/Objective(s):To evaluate the outcomes of conventional preoperative radiation therapy (preop-RT) followed by surgery for soft tissue sarcoma (STS) of the extremity and trunk. Materials/
Methods: A retrospective review was conducted using a prospectively maintained database of STS patients from a single sarcoma center (11/2000 - 09/2020). All patients underwent conventional preop-RT (50 Gy/25 fractions) utilizing either 3D-Conformal Radiation Therapy (3D-CRT) or Image-Guided Intensity Modulated Radiation Therapy (IG-IMRT), followed by surgery after 4-6 weeks. The primary focus was major wound complications (MWC) rates and oncological outcomes. The long-term functional outcome was assessed using the Musculoskeletal Tumour Society Rating Scale (MSTS) and the Toronto Extremity Salvage Score (TESS). Results: Median follow-up was 5.9 (0.5-24.6) years among 1140 patients, of whom 761 had IG-IMRT and 379 had 3D-CRT. The most common histologies were myxofibrosarcoma (13%), undifferentiated pleomorphic sarcoma (11%), and myxoid liposarcoma (11%). Tumors>10 cm were observed in 32% (360/1125), and 88% (960/1090) had grade II-III tumors. Positive microscopic margins were found in 15% (166/1137) of patients. The overall incidence of MWCs was 24% (271/1110), with 28% for 3D-CRT and 23% for IG-IMRT (p=0.077). Comparative analysis of the IG-IMRT and 3D-CRT cohorts revealed no significant differences in 5-year local recurrence rate (6.0% vs 4.8%; p=0.549), 5-year disease-free survival (69% vs 70.1%; p=0.519), 5-year overall survival (78.5% vs 76.3%; p=0.195), and 5-year distant metastatic rate (27% vs 26.6%; p=0.590), respectively. Additionally, the multivariable analysis indicated that 3D-CRT, large tumor size (>10 cm), and tumors located in the lower extremity significantly increased the risk of MWCs, with odds ratios of 1.40 (95%CI 1.04-1.89; p=0.025), 1.49 (95%CI 1.11-1.99, p=0.008), and 2.84 (95%CI 1.86-4.33, p<0.001), respectively. There was no significant difference in TESS and MSTS scores between IG-IMRT and 3D-CRT, with mean overall scores of 84.5 and 83.6 (p=0.73) and 89.4 and 86.4 (p=0.35), respectively. Conclusion: Conventional preop-RT followed by surgery provided favorable outcomes for STS patients with acceptable MWC rates. IG-IMRT may be the preferred RT technique due to its marginally lower MWC rates. These findings may provide a contemporary (conventionally fractionated) standard for comparison with new hypofractionated preoperative RT protocols.
