Radiation Therapy Techniques in the Management of Locally-Advanced, High-Grade, Soft-Tissue-Sarcoma

Abstract

<h3>Purpose/Objective(s)</h3> Assess which prognostic factors affect local recurrence (LR) rates and wound complications of locally-advanced, high-grade, soft-tissue-sarcoma (STS). <h3>Materials/Methods</h3> Retrospective analysis was performed on patients 2005 to 2018, with high-grade STS of extremity or trunk, >5cm, histology specific, with central pathology review. Wide-excision was performed in 100 patients along with radiation, whose radiation fields and dose plans were available for review, of which 31 also received Ifosfamide-Doxorubicin, with a minimum follow-up of 1-year. Multi-variable-analysis (MVA) of prognostic factors were calculated to see which variables affected LR, and nonhealing wound rates. <h3>Results</h3> Median follow-up was 5.8 years. Univariate analysis revealed that trunk location, proximal, distal, and radial clinical-target-volume (CTV) margins of 1.5cm had higher rates of LR vs ≥2cm or presence of fascial boundary. MVA of these prognostic factors revealed that trunk location (p=0.048), and radial CTV of 1.5cm (p=0.006) independently predicted for higher LR, as 10 of 15 LR were at the edge of the radial margin. Bolus did not affect LR. The odds ratio for nonhealing wounds at 3 months were higher for T2a disease, larger tumor size, proximal CTV ≥2cm, wider field size, use of chemotherapy, and bolus technique. <h3>Conclusion</h3> Proximal/distal CTV margins of 3cm seem adequate, but high-grade STS ≥ 5cm may benefit from increased radial CTV margins of 2-2.5cm in the absence of a fascial boundary, although larger CTV may increase nonhealing wound rates. Bolus techniques lead to higher wound complications in T2a-b STS, and should be avoided.