RADT-36. A SINGLE-CENTRE EXPERIENCE WITH HYPERARC FRACTIONATED STEREOTACTIC RADIOSURGERY [FSRS] FOR BENIGN BRAIN TUMOURS

Abstract

Abstract BACKGROUND Treating benign brain tumours with fSRS may have radiobiologic and clinical advantages, such as lower rates of symptomatic oedema and radionecrosis[1]. HyperArc (HA, Varian Medical System) is an isocentric VMAT technique developed for non-coplanar, MLC-based stereotactic radiotherapy with automated optimizations and delivery. Here we report our initial clinical experience of HyperArc fSRS in treating benign brain tumours. MATERIALS AND METHODS We retrospectively reviewed 21 cases of benign brain tumours treated at the Bon Secours Radiotherapy Cork between May 2020-May 2023. Clinical and dosimetric parameters are reported. RESULTS A total of 21 patients were treated in a total of 105 SRS fractions, all using a 5-fraction regimen (5x5Gy, N = 20). The commonest tumour was meningioma (N = 9), followed by vestibular schwannoma (N = 7) and pituitary adenoma (N = 5). Median patient age was 59 years (range 26-86). Median PTV was 4.65 cc (IQR 1.9-14.6), median number of arcs was 4 (range 3-4), median PTV coverage was 99.6 % (IQR 98.0-99.9). Median prescription isodose was 79%. Median Paddick conformity index and gradient index was 0.86 (IQR 0.83-0.98) and 3.0 (IQR 2.9-3.2) respectively. Median follow-up was 7 months. No patient suffered from toxicity ≥ grade 2 (Common Toxicity Criteria, Version 5). Only 2/21 patients required steroid therapy during fSRS. No patient had a seizure. CONCLUSION HyperArc fSRS is a feasible option for benign brain tumours. Initial clinical experience in terms of plan quality and acute toxicity is encouraging. fSRS for benign brain tumours should be prospectively studied. REFERENCES: 1. Lehrer EJ et al IJROBP 2019 Mar1;103(3):610-630