ESTRO 2024 - Abstract Book

S804

Clinical - CNS

ESTRO 2024

better understanding of RICE risk factors is crucial to improve management and offer adaptive therapy at the outset and during follow-up. In the present study, we explore known cardiovascular risk factors associated with the development of ischemic strokes in their association with the evolution of RICE.

Material/Methods:

In the present study, we analyzed 190 consecutive adults diagnosed with low-grade glioma who underwent PRT between 2010 and 2020 at our institution. Analysis was performed in a retrospective fashion and longitudinally over the entire follow up period for in median 5.6 years using routine clinical exams and follow-up magnetic resonance imaging (MRI). Assessed pretherapeutic vascular risk factors (VRF) included the following: Age, sex, arterial hypertension, diabetes mellitus, dyslipidemia, body mass index (BMI) (based on height and weight), overweight (BMI ≥25), and tobacco abuse. In addition, we reviewed manifestation of (cardio -)vascular diseases including history of stroke, myocardial infarctions, thrombembolism, coronary artery disease, peripheral artery disease and chronic kidney disease. We defined RICE as new non-tumor-related post-treatment contrast enhancement on cMRI in surrounding brain tissue within the 80% isodose region, analogous to RANO criteria, during the follow-up period. Every retrospectively suspected RICE case was presented at an interdisciplinary tumor board conference. Primary Endpoint of the study was RICE occurrence. Secondary endpoints were time latency to RICE occurrence, RICE severity (documented by CTCAE grading), RICE treatment and RICE outcome. Analysis of vascular risk factors for RICE occurrence demonstrated age to be an important risk factor with patients ≥50 years relative to patients <50 years being at two -fold risk for RICE (p=0.024). Arterial hypertension and diabetes mellitus were associated with a 2.7-fold risk for RICE (p=0.00012) and a 11.7-fold risk for RICE (p=0.0066), respectively, and were the two most important vascular risk factors for RICE development. Other vascular risk factors including dyslipidemia (2.1-fold), overweight (2.0-fold), smoking (2.6-fold) and history of any manifest vascular diseases also demonstrated a higher rate of RICE, but threshold for significance was not reached for the descriptive group difference. For manifest vascular diseases, history of stroke as well as history of any thromboembolism, peripheral artery disease and chronic kidney disease were 1.6 to 1.9-fold found in the RICE subgroup compared to the non-RICE subgroup, but only peripheral artery disease reached the threshold for significance (p=0.024). RICE-free survival was calculated for all vascular risk factors and vascular diseases and demonstrated RICE to be more frequent and to occur earlier in patients with vascular risk factors or diseases. Overall, RICE was mitigating and resulted in the relevant number of 27.7% in CTCAE °3, so patients needed RICE directed therapy like dexamethasone or Bevacizumab. In this cohort, complete RICE remission was not observed during the follow-up period which supports that RICE is a long-lasting sequela. Multivariable regression modelling including the vascular risk factors age (≥40 years, cutoff set based on median age in the cohort), sex, arterial hypertension, overweight and smoking showed that age (p=0.05) and arterial hypertension (p=0.01) were independent risk factors for RICE occurrence. Analyzing risk factors for time latency from radiotherapy to first occurrence of radiation-induced contrast enhancements (RICE) in a multivariable linear regression model including age (≥40 years), sex, arterial hypertension, diabetes mellitus, dyslipidemia, overweight and smoking demonstrated male sex (p=0.02), arterial hypertension (p=0.006), diabetes mellitus (p=0.0008) and smoking (p=0.001) to be independently of each other and other vascular risk factors to influence time latency from radiotherapy to RICE occurrence. Results:

Conclusion: