ESTRO 2024 - Abstract Book

S5389

Radiobiology - Tumour biology

ESTRO 2024

1846

Digital Poster

Determinants of cerebral radionecrosis in animal models: a systematic review

Sanaria Al-Rubaiey 1,2 , Carolin Senger 2 , Jan Bukatz 1,2 , Kiril Krantchev 1,2 , Anastasia Janas 1 , Melina Nieminen-Kelhä 1 , Susan Brandenburg 1 , Daniel Zips 2 , Peter Vajkoczy 1 , Güliz Acker 1,2 1 Charité - Universitätsmedizin Berlin, Department of Neurosurgery, Berlin, Germany. 2 Charité - Universitätsmedizin Berlin, Department of Radiation Oncology, Berlin, Germany

Purpose/Objective:

Stereotactic radiosurgery (SRS) is a treatment approach in radiation oncology that is well established in clinical routine for the management of brain tumors, especially brain metastases. Radionecrosis (RN) is a common complication of this treatment that is generally defined as an intense local tissue reaction that may occur after RT. The mechanisms and risk factors involved in the development of this adverse effect have yet to be fully explored. Preclinical animal studies are required to understand the complicated pathogenesis and underlying radiobiology and to further analyze the risk factors and potential targets for the prevention and treatment of radionecrosis. To summarize the current state of knowledge on this clinically highly relevant topic, we conducted this literature review.

Material/Methods:

We performed a systematic literature search based on the PRISMA guidelines using PubMed, Ovid, and Web of Science databases. We conducted the search using predefined terms and the complete search strategy can be found as a preregistered protocol on PROSPERO (CRD42023361662). To minimize the different types of bias and maintain the validity of our results, we used the standardized and well-established SYRCLE risk-of-bias assessment tool and the CAMARADES checklist to assess the methodological quality of the studies [1, 2]. We retrieved 75 studies for further examination. In this review, we summarize important findings regarding the induction of radionecrosis.

Results:

We included 75 studies with most studies involving healthy animals (n = 65,86.67%) (Fig. 1). In these studies, high doses of irradiation of 35–40 Gy in rats and 50 Gy in mice led repeatedly to radionecrosis among different studies and set-ups. Higher dose and larger irradiated volume were associated with earlier onset. Fractionated concepts also lead to necrosis despite subnecrotic single doses, with a correspondingly high applied total dose. Distinct anatomical brain structures respond to irradiation in various ways, with for example the hippocampus, particularly the cornu ammonis region, being highly sensitive to irradiation. White matter appears to be more vulnerable to irradiation than gray matter. Younger age, more evolved animal species, and BALB/c genetic background were also significant factors, whereas sex was irrelevant. With regard to tumor associated radionecrosis, only 13.33% of the studies were performed on tumor bearing animals. All of these covered glioma (40%), gliosarcoma (20%), or glioblastoma models (40%). There are conflicting reports on the impact of irradiation on intratumoral necrosis in high-grade glioma models.