ESTRO 2025 - Abstract Book

S726

Clinical - CNS

ESTRO 2025

To discriminate between progression or radionecrosis (RN), symptoms and MR image were review along the follow up considering the multidisciplinary opinion for the diagnosis. MR every three months was realized. Kaplan Meier curves were used to analyse OS and DFS. Results: With a median follow-up of 17 months (2-19) OS was 49.5% and DFS was 43.5%. The median total dose was 30Gy to 6Gy per fraction. The second scheme of treatment most used was 27Gy in three fractions every other day. 85,5% no presented symptomatic edema, in 7,2% cases, edema in MR was observed and in 7,2% steroids treatment were required. The median GTV volume was 10.94 ml (0.04-128ml). The median Brain-GTV V30 was 12.87 (0-79), V25 was 29.25 (0 128), V20 was 41.91 (3.35-290) and V12 was 108.84 (9.95-591). In the multinominal logistic regression no significant statistical relationship between V20 (p 0,487) PTV (p 1,208) or GTV volumes (p 0,181) and radionecrosis were found. Total dose (p 0), V25 (p 0,041) and V30 (0,041) in brain- GTV were statistical related between with symptomatic RN (ODS 1,524) 95% IC (1,018-2,282). Conclusion: To conclude, fSRS is a safe treatment for brain metastases without causing serious toxicity to healthy tissues. The relationship between dosimetric parameters: V25, V30 and total dose must be exhaustively analyse in treatment plannings for fSRS in five or three fractions to predict RN risk.

Keywords: fSRS, Dosimetric parameters, Toxicity.

References: 1.

Eaton BR, Gebhardt B, Prabhu R, Shu HK, Curran WJ, Crocker I. Hypofractionated radiosurgery for intact or resected brain metastases: defining the optimal dose and fractionation. Radiat Oncol. diciembre de 2013;8(1):135. 2. Milano MT, Grimm J, Niemierko A, Soltys SG, Moiseenko V, Redmond KJ, et al. Single- and Multifraction Stereotactic Radiosurgery Dose/Volume Tolerances of the Brain. Int J Radiat Oncol. mayo de 2021;110(1):68-86.

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Digital Poster Efficacy and safety of postoperative hypofractionated stereotactic radiotherapy for resected brain metastases: a single-centre experience Anna Lucas Calduch 1 , Miquel Macià Garau 1 , Nagore García Expósito 1 , Gerard Plans Ahicart 2 , Aleix Rosselló Gómez 2 , Alejandro Fernández Coello 2 , Noemí Vidal Sarro 3 , Ismael Sancho Kolster 4 , Ignasi Modolell Farré 4 , Laura Martínez Ávila 1 , Carles Majós Torró 5 , Albert Pons Escoda 5 , Pere Cifre Serra 2 , Jordi Bruna Escuer 6 1 Radiation Oncology, Institut Català d'Oncologia, L'Hospitalet de Llobregat (Barcelona), Spain. 2 Neurosurgery, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat (Barcelona), Spain. 3 Pathology, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat (Barcelona), Spain. 4 Medical Physics, Institut Català d'Oncologia, L'Hospitalet de Llobregat (Barcelona), Spain. 5 Radiology, Institut de Diagnòstic per la Imatge, L'Hospitalet de Llobregat (Barcelona), Spain. 6 Neurology, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat (Barcelona), Spain Purpose/Objective: The addition of radiotherapy (RT) enhances local control following surgical resection of brain metastases (BM). Hypofractionated stereotactic radiotherapy (HFSRT) is a highly effective option, however it entails several uncertainties related to the volumes contouring, which may increase the risk of local control failure and/or the development of radionecrosis (RN).