ESTRO 2024 - Abstract Book

S752

Clinical - CNS

ESTRO 2024

1 Maastricht University Medical Center, Department of Radiation Oncology, Maastricht, Netherlands. 2 Maastricht University Medical Center, Department of Medical Psychology, Maastricht, Netherlands. 3 Maastricht University Medical Center, Department of Neurology, Maastricht, Netherlands. 4 Libera Università Vita-Salute San Raffaele, School of Medicine, Milan, Italy

Purpose/Objective:

Deterioration of neurocognitive function in adult patients with a primary brain tumor is the most concerning side effect of radiotherapy. This study was aimed to develop and evaluate Normal-Tissue Complication Probability (NTCP) models using clinical and dose-volume measures for 6-month, 1-year and 2-year Neurocognitive Decline (ND) post-radiotherapy.

Material/Methods:

Consecutive patients with a primary brain tumor treated with radical photon and/or proton radiotherapy (RT) between March 2019 and December 2022 were included. Controlled Oral Word Association (COWA) test, Hopkins Verbal Learning Test-Revised (HVLTR) and Trail Making Test (TMT) were used to objectively measure ND. The reliable change index was calculated to identify the change that is unlikely to occur due to error of measurement. A comprehensive set of potential clinical and dose-volume measures on several brain structures (total brain structure, hippocampus (left, right and entire structure), hypothalamus (left, right and entire structure), brainstem (interior, surface and entire structure), cerebellum and pituitary gland) were considered for statistical modelling. Clinical, dose-volume and combined models were constructed and internally tested in terms of discrimination (Area Under the Curve, AUC), calibration (plot and Mean Absolute Error, MAE) and net benefit.

Results:

A total of 219 patients (age at RT initiation: 54.4±14.9 years, 47% male) were included. Histological types were meningioma (n=56, 26%), glioblastoma (n=49, 22%), astrocytoma (n=43, 20%), oligodendroglioma (n=35, 16%) and other (n=36, 16%). WHO tumor grades were I in 51 (23%), II in 78 (36%), III in 30 (14%) and IV in 49 (22%) patients. The tumor was located in the left and right hemispheres in 88 (40%) and 111 (51%) patients, respectively. The predominant tumor location was in the frontal (n=82, 37%), temporal (n=45, 21%) and parietal (n=29, 13%) lobes. Tumor resection was performed in 165 (75%) patients prior to RT. Sequential and concurrent sequential chemotherapy was performed in 74 (34%) and 51 (23%) patients, respectively. Chemotherapy agents were temozolomide in 91 (42%) and procarbazine, lomustine and vincristine in 34 (16%) patients. Photon, proton and combined RT was performed for 118 (54%), 24 (11%) and 77 (35%) patients, respectively. 53.7%, 42% and 46.5% of the patients developed ND at 6-month, 1-year and 2-year timepoints, respectively. Following predictors were included in the combined model for 6-month ND: age at diagnosis>54 years (OR=3.52), overweight (OR=0.4), obesity (OR=0.22), high education level (OR=0.36), sequential (OR=2.9) and concurrent sequential chemotherapy (OR=3.55), cerebellum D0.03cc≥62.1Gy (OR=9.68), brainstem volume≥27.3cc (OR=0.32) and hypothalamus volume≥0.51cc (OR=0.39). Patients with a tumor in the temporal lobe, one false positive answer in baseline HVLTR delayed recognition, TMT part B completion time≥56 seconds, GTV≥21.7cc, brain D0.03cc≥56.6Gy and brainstem D0.03cc≥0.49Gy were shown to be at higher risk of 1 -year ND. Longer duration between surgery and radiotherapy, baseline antithrombotic use and brain volume≥1214cc were found to be protective factors for 1 -year ND. At the 2-year timepoint, patients with middle education level (versus low), tumor in the right lobe (versus left)