Preoperative ultra-hypofractionated radiotherapy for soft-tissue sarcomas: low rate of wound complications

Abstract

Background: Normofractionated pre-operative radiotherapy (nRT) with 50 Gy applied in 25 fractions represents the most widely used radiotherapy (RT) regimen in combined local treatment of soft tissue sarcomas (STS). STS are characterized by a low α/β ratio of 4-5 Gy, which may translate into a higher sensitivity for hypofractionation. Increasing data from cohorts and phase II trials on ultra-hypofractionated RT (uhRT) regimens is available. We prospectively assessed our preoperative uhRT sarcoma patient cohort with a focus on short term wound complications (WC). Methods: This is a prospective registry analysis of a single center patient cohort, treated from 03.2020-10.2023 with uhRT (25 Gy in 5 fractions in 1 week). The same radiation oncologists (GS/CG) and surgeon (BF) performed the treatment (61/61 and 58/60), as well as the same reference pathologist (BB) confirmed all histopathological diagnoses. WC (according to CAN-NCIC-SR2 trial) and intermediate local control (LC) rates were assessed and compared with outcome data of a previously published cohort of 67 extremity/trunk sarcoma patients treated with nRT by the same authors (7% WC, 98% LC at 3 years). Results: After a mean/median follow-up (FU) of 19/19 months (range 0-46), LC at 1.5y was 94%. Surgery was performed at a mean/median of 20/16 days (range 4-60) after uhRT completion. WC were observed in 7/60 operated patients (12%), and in 5/51 (10%) extremity/trunk lesions. Early tolerance was excellent, limited to G0-1, even in 3 patients with prior RT to the same region. Clear resection margins were achieved in 55/60 patients (92%). Pathologic necrosis of ≥95% was reported in 5%, 75% achieved less than <50% necrosis. Conclusion: These results show low rates of WC and high LC for uhRT and are comparable to our previously published nRT data. This study supports the routine use of preoperative uhRT for STS.