ESTRO 2021 Abstract Book

S469

ESTRO 2021

Conclusion Of the previously reported dose dependent cortical thinning only the posterior cingulate region could be verified in the current patient population. For our population, the local dose values in this posterior cingulate region was on average higher that the remaining regions and it is likely that a population with a different distribution of regional doses would result in different cortical thinning. Currently a prospective study is running with the aim to expand the population to get a more exhaustive distribution of local doses to the different cortical regions. References: [1] doi:10.1093/noajnl/vdaa060 [2] doi:10.1016/j.ijrobp.2017.01.005 PH-0603 Clinical implementation of standardized neuro-cognitive assessment after radiation to the brain C. Zegers 1 , C. Offermann 1 , J. Dijkstra 2 , I. Compter 1 , F. Hoebers 1 , D. de Ruysscher 1 , M. Anten 1 , W. Backes 3 , A. Postma 4 , W. van Elmpt 1 , D. Eekers 5 1 Maastricht University Medical Center+, GROW School for Oncology, Department of Radiation Oncology (Maastro), Maastricht, The Netherlands; 2 Maastricht University Medical Center+, Department of Medical Psychology , Maastricht, The Netherlands; 3 Maastricht University Medical Center+, MHeNs School for Mental Health and Neuroscience, Department of Radiology & Nuclear Medicine , Maastricht, The Netherlands; 4 Maastricht University Medical Center+, MHeNs School for Mental Health and Neuroscience, Department of Radiology & Nuclear Medicine, Maastricht, The Netherlands; 5 Maastricht University Medical Center+, GROW School for Oncology, 1. Department of Radiation Oncology (Maastro), Maastricht, The Netherlands Purpose or Objective Radiotherapy induced impairment of cognitive function can lead to premature loss of independence and reduced quality of life. The aim of this study is to describe the first results of standardized neuro-cognitive assessment in clinical routine, by defining the number and extend of cognitive decline for patients receiving a radiation dose to the brain. Materials and Methods Patients treated for a neurological tumor, prophylactic cranial irradiation (PCI) or head and neck cancer (HN; with radiation dose in the brain) in our clinic between April-2019 and- Feb 2021 were included. Patients performed a memory test, the Hopkins Verbal Learning Test (HVLT), and two attention tests, the Controlled Oral Word Association Test (COWA) and Trail Making Test A&B (TMT-A; TMT-B) before the start of radiation, 6 months (6m) and 1 year (1y) after irradiation. The Reliable Change Index (RCI) between baseline and follow-up at 6m or 1y was calculated using reference data from literature. Exceeding 90% CI for the RCI was defined as a significant change in neuro-cognitive functioning. We identified patients with a significant decrease on at least one test or at least two tests (incl. at least HVLT-total recall), and evaluated significant differences in median dose parameters by using the Wilcoxon Signed rank test. Results Data of baseline and 6m measurements were available for 152 patients. The combination of baseline and 1y for 71 patients. At 6m a significant decline was observed in 16% of the patients for HVLT-total recall, 17% for HVLT-delayed recall, 6% for COWA, 22% for TMT-A and 25% for TMT-B. At 1y we observed a significant decline in 18% for HVLT-total recall, 18% for HVLT-delayed recall, 3% for COWA, 19% for TMT-A 19% and 25% for TMT-B. In total 46% of the patients showed a significant decline in at least one of the neuro-cognitive tests at 1y (HH, N=18; Neu, N=10; PCI N=5) and 14% on at least 2 of these neuro-cognitive tests at 1y (HH, N=3; Neu, N=5; PCI N=2). The median doses were higher for patients with a decline on at least one test, but not significantly different; D mean Brain (3.6Gy vs 3.2Gy), Hippocampus (1.4Gy vs 1.2Gy) or Cerebellum (5.1Gy, vs 3.0Gy). For patients with a significant decline on at least two tests the median doses were: D mean Brain (10.4Gy vs 3.2Gy, P=NS), Hippocampi (4.3Gy vs 1.2Gy, P=NS) and Cerebellum (3.2 vs 3.4Gy, P=NS). Conclusion Cognitive changes after radiotherapy were measured using neuro-cognitive tests in clinical routine. Approximately half of the patients treated with a radiation dose to the brain showed a significant decline on at least one of the test variables at 1y after treatment. The preliminary results show a trend towards a higher median D mean in the brain, cerebellum or hippocampi for patients with a cognitive decline. We will further