ESTRO 2021 Abstract Book

S871

ESTRO 2021

Conclusion A clear trend towards shorter and less aggressive treatments was seen in our department.

Target treatments such as SRS and FSR can be a safe option in intracranial tumors being a more comfortable option for patients by reducing side effects and overall treatment time with similar local control and toxicity. This reduces the waiting list making possible to treat more patients in the same time.

PO-1046 Multifraction stereotactic radiotherapy for brain metastases: initial experience. S. Heylen 1 , M. Lambrecht 1 , G. Defraene 2 , B. Vanstraelen 1 , A. Nulens 1 , L. Estera Tilea 3 , J. Daisne 1 , P. Berkovic 4 1 University Hospital of Leuven, Radiation oncology, Leuven, Belgium; 2 KULeuven, Laboratory of Experimental Radiotherapy, Leuven, Belgium; 3 Hospital de la Santa Creu i Sant Pau, Radiation Oncology, Barcelona, Spain; 4 University Hospital of Leuven, Radiation Oncology, Leuven, Belgium Purpose or Objective The use of local treatment modalities such as stereotactic radiotherapy (SRT) for patients with one or multiple brain metastases (BM) from solid tumor origin is increasing. Multifraction (MF) SRT holds a potential benefit over single shot stereotactic radiosurgery (SRS) as preliminary data have shown that MF-SRT might decrease the incidence of radionecrosis (RN) while maintaining local control rates. At the University Hospitals Leuven, MF-SRT for BM was introduced in April 2017, replacing SRS as the modality of choice for patients with one or more BM. In this study we aim to retrospectively analyze the outcome and risk of RN of patients treated in our institution with MF-SRT for BM. Materials and Methods All patients with BM treated with MF-SRT from April 2017 to September 2019 in the University Hospital of Leuven, were retrospectively reviewed . Both patients with and without prior resection were included. The