Abstracts iii9 NEURO-ONCOLOGY ADVANCES • AUGUST 2023 ABSTRACT CITATION ID: vdad070.032 CLRM-10 ENHANCED PATIENT CARE FOR BRAIN METASTASIS PATIENTS UTILIZING A DEDICATED METASTASIS TUMOR BOARD Lisa Rogers, Adam Robin, Mira Shah, Salim Siddiqui, Jim Snyder, Tobias Walbert, Ian Lee, Tom MIkkelsen, Jack Rock, Lisa Scarpace; Henry Ford Health, Detroit, Michigan, USA BACKGROUND: Patients with brain metastases are a heterogeneous population. In contrast to patients with primary brain tumors, these patients require individualized therapy based on the type and status of systemic cancer, number and volume of brain metastases, anticipated ef- fcacy of therapy and survival. Therapeutic options for brain metastasis; surgical, radiation and precision medicine approaches have increased in recent years as has survival for a number of cancers, leading to more so- phisticated care. To meet this challenge in January 2023 we organized a dedicated brain metastasis tumor board. METHODS: We reviewed the number of total patients, and those newly-diagnosed, presented at the dedicated brain metastasis board in the frst 10 weeks of 2023 as com- pared with the same time interval the prior year where similar cases were presented at a general brain tumor board. We also assessed change in prac- tice pattern based on the dedicated metastasis tumor board. RESULTS: 89 patients were presented in the frst 10 weeks of 2023, including 75 who were newly diagnosed.  The total number and those newly diagnosed are 17% higher than the prior year.  The dedicated brain metastasis board, staffed by experts in brain metastases, allowed for earlier identifcation of patients eligible for clinical trial and additionally our review of pa- tients identifed the need for standardizing advanced imaging techniques including high resolution, higher contrast-dose MRI scans for better as- sessment of brain metastases across our hospital sites. CONCLUSION: We found that a dedicated brain metastasis board increased the number of patients presented for multidisciplinary review, including new patients, which served to better identify those eligible for clinical trial. It led to a consensus to incorporate advanced imaging techniques for assessing treat- ment response. The experience is superior to inclusion of these patients in a general brain tumor board. ABSTRACT CITATION ID: vdad070.033 CLRM-11 ALK TYROSINE KINASE INHIBITOR THERAPY AND BRAIN METASTASES IN NON-SMALL CELL LUNG CANCER: IMPACT ON TUMOR SIZE AND DISTRIBUTION David Olayinka Kamson, Tia Cheunkarndee, Kristen Marrone, Joseph Murray, Joy Feliciano, Christine Hann, David Ettinger, Valsamo Anagnostou, Patrick Forde, Julie Brahmer, Benjamin Levy, Susan Scott, Vincent Lam; Johns Hopkins University, Baltimore, USA Non-small cell lung cancer (NSCLC) with anaplastic lymphoma kinase rearrangement (ALK+) is known to have a high propensity to form brain metastases (BrM), with over 50% of ALK+ lung cancer patients developing BrM despite effective ALK tyrosine kinase inhibitor (TKI) therapy with central nervous system (CNS) activity. Pharmacokinetic (PK) data from other CNS-active lung cancer TKIs have suggested that there may be differences in drug concentration between white and gray matter in the brain, which may play a role in BrM formation patterns and response. In this study, we aimed to compare the size and distribu- tion of ALK+ NSCLC BrMs at diagnosis in a TKI-naïve and TKI-exposed cohort. Brain MRI data from patients with ALK+ NSCLC were retro- spectively reviewed, and each tumor was marked in a standard space brain model using 3D Slicer-4.11. FreeSurfer white-gray matter atlases were used to assess BrM distribution. We found that TKI-exposed patients had signifcantly smaller BrM diameters than TKI-naïve patients (6.1±3.8 vs. 10.2±5.5mm, p=0.02) and were more likely to have white matter- exclusive (3.5±4.4 vs. 1.4±2.0, p=0.05) and deep white matter metastases (3.2±4.3 vs. 1.3±2.0, p=0.06). The metastatic burden was similar between the groups, while the mean number of BrM per patient was numerically higher in the TKI-exposed group (10.6±11.9 vs. 6.2±9.5; p=0.22). These fndings suggest that TKI therapy may result in smaller individual lesions that are more likely to be exclusive to the white matter, where drug con- centrations may be signifcantly lower. This suboptimal CNS distribution of TKIs in the white matter may contribute to the progression of brain metastases in ALK+ patients despite TKI therapy. Further analyses are on- going to evaluate ALK TKIs of varying CNS penetrance and later disease time points in more granular anatomic regions. FINAL CATEGORY: LOCAL AND MULTIMODALITY APPROACHES ABSTRACT CITATION ID: vdad070.034 LMAP-03 OUTCOME OF BRAIN METASTASES TREATED WITH GAMMA KNIFE STEREOTACTIC RADIOSURGERY (GKSR): COHORT RETROSPECTIVE STUDY ON 205 CASES Nourou Dine Adeniran Bankole, Adyl Melhaoui, Yasser Arkha, Afaf Semmar, Khalid Bouyakhlef, Mahjouba Boutarbouch, Mohamed Jiddane, Abdeslam El Khamlichi; Gamma Knife Radiosurgery Unit, National Center for Rehabilitation and Neuroscience, ,Mohamed V university of Rabat, Rabat-Morocco, Rabat, Morocco BACKGROUND: Brain metastases (BMs) are the most common expan- sive intracranial lesions in adults. Approximately 50% of patients diagnosed with new brain metastases have more than one brain metastasis at the time of diagnosis. OBJECTIVE: We report our experience of brain metastases treated with GKSR and evaluate the outcome. METHODS: Patients treated by Gamma Knife stereotactic radiosurgery (GKSR) in our institution be- tween 2008 and 2021 for BM were recorded retrospectively. RESULTS: A total of 205 patients (56.6% females) were included, with a median age of 59 (25-83) years old. Breast (n=85, 42.5%) and lung (n=76, 38%) were the common original locations for the primary tumors (Table 1). There were 103 patients (50.3%) with single BM and 102 patients (49.7%) with mul- tiple BM⩾2. The median number of multiple BM treated was 4 (2-43). The overall mean survival time was 6.00(95% CI, 5.07-6.93) months for all BM. The median percentage of tumor control after radiosurgery treatment was 65% (20-99) over the median follow-up time of 6.00(3-84) months. In the overall population, the 1-year OS rate was 37.55%, the 2-year OS rate was 25.12%, and the 5-year OS was 18.51%. The mean survival time among pa- tients with BM was higher in those with multiple BM than those with single BM ([10 (95%CI 6.67-13.33) months vs 5(4.21-5.70) months, P (0.03)]). Retreatment, tumor stability (control), and progression infuence the overall survival of BM, whether single or multiple (P<0.001). CONCLUSION: Stereotaxic Radiosurgery provides good results in terms of Overall survival and better Quality of Life for BM, whether single or multiple. Stability and retreatment infuenced the overall survival of BM.Keywords: Brain metas- tasis, Gamma knife, stereotaxic Radiosurgery, Cancer. ABSTRACT CITATION ID: vdad070.035 LMAP-04 CHOOSING WISELY BETWEEN RADIOTHERAPY DOSE- FRACTIONATION SCHEDULES: THE MOLECULAR GRADED PROGNOSTIC ASSESSMENT (MOLGPA) FOR ELDERLY GLIOBLASTOMA (EGBM-MOLGPA) Hye In Lee 1 , Jina Kim 2 , In Ah Kim 3 , Joo Ho Lee 1 , Jaeho Cho 2 , Hong In Yoon 2 , Chan Woo Wee 4 ; 1 Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea, Republic of. 2 Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea, Republic of. 3 Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea, Republic of. 4 SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, Korea, Republic of This study aimed develop a prognostic model integrating genomic characteristics in patients with elderly glioblastoma (eGBM), and com- pare the effcacy between conventionally fractionated radiotherapy (CFRT) vs. hypofractionated radiotherapy (HFRT). Patients aged ≥65 years who underwent radiotherapy for IDH-wildtype eGBM between 2006 and 2021 were included. Patients planned for a ≥6-week or ≤4-week radiotherapy were regarded as being treated with CFRT (334 patients; median, 60 Gy in 30 fractions) or HFRT (239 patients; median, 45 Gy in 15 fractions), respectively. We developed the molecular graded prognostic assessment score for eGBM (eGBM-molGPA) and assigned 0.0, 0.5, and 1.0 points in proportion to the corresponding hazard ratio (HR) of each prognostic factor for overall survival (OS). Temozolomide- based chemoradiation was applied for 86% of patients. With a median follow-up of 17.4 months, the median OS was 18.7 months for CFRT plus temozolomide group, 15.1 months for HFRT plus temozolomide group, and 10.4 months for RT alone group. The eGBM-molGPA was established based on prognostic factors from multivariate analysis Downloaded from https://academic.oup.com/noa/article/5/Supplement_3/iii9/7237140 by guest on 06 August 2023