Novel Postoperative Hypofractionated Accelerated Radiation Dose-Painting Approach for Soft Tissue Sarcoma

Abstract

Background: Hypofractionated radiotherapy (RT) offers benefits in the treatment of soft tissue sarcomas (STS), including exploitation of the lower α/β, patient convenience, and cost. This study evaluates the acute toxicity of a hypofractionated accelerated RT dose-painting (HARD) approach for postoperative treatment of STS. Materials and Methods: This is a retrospective review of 53 consecutive patients with STS who underwent resection followed by postoperative RT. Standard postoperative RT dosing for R0/R1/gross disease with sequential boost (50Gy + 14/16/20Gy in 32-35 fractions) were replaced with dose-painting, which adapts dose based on risk of disease burden, to 50.4 and 63/64.4/70 Gy in 28 fractions, respectively. The first 10 patients were re-planned with a sequential boost RT approach and dosimetric indices were compared. Time-to-event outcomes, including local control (LC), regional control (RC), distant control (DC), and overall survival (OS), were estimated with Kaplan-Meier (KM) analysis. Results: Median follow up was 25.2 months. Most patients had high grade (59%) STS of the extremity (63%) who underwent resection with either R1 (40%) or close (36%) margins. Four patients experienced grade 3 acute dermatitis which resolved by the 3-month follow up visit. The 2-year LC, RC, DC, and OS were 100%, 92%, 68%, and 86%, respectively. Compared to the sequential boost plan, HARD had a significantly lower field size (total V50Gy) (p=0.002), bone V50 (p=0.031), and maximum skin dose (p=0.008). Overall treatment time was decreased by 4-7 fractions, which translated to a decrease in estimated average treatment cost of $3,056 (range: $2,51-$4,335, p<0.001). Conclusions: In addition to benefits in cost, convenience, and improved biological effect in STS, hypofractionated accelerated RT dose-painting (HARD) regimen offers a safe treatment approach with dosimetric advantages compared to conventional sequential boost, which may translate to improved long-term toxicity.