NCOG-03. IMPACT OF THE RATE OF RADIOGRAPHIC RESPONSE (RR) OF BRAIN METASTASES (BM) TO WHOLE BRAIN RADIATION THERAPY (WBRT) ON NEUROCOGNITIVE FUNCTION (NCF) ON NRG-CC001

Abstract BACKGROUND The assessment of BM response to WBRT and its impact on NCF in clinical trials has been limited by lack standardized imaging protocols. NRG-CC001 is a randomized trial requiring pre-specified MRI protocols at baseline 6-months, providing uniform dataset investigate if RR correlates with changes. METHODS patients hippocampal avoidance (HA-WBRT) or WBRT. was analyzed using 6-month change scores deterioration, defined the reliable index. Chi-square t-tests were used for pretreatment characteristic comparisons. Inter-rater reliability between central institutional assessed weighted kappa, κ. Linear regression test trends across types multivariable logistic association deterioration. RESULTS 149 135 evaluable assessment, respectively. Pretreatment characteristics well-balanced, except post-high school education (70.6% HA-WBRT vs. 52.5% WBRT, p=0.023). fair (κ=0.36). There no difference arms (p=0.41) overall rates 14.1% CR, 42.2% PR, 17% SD, 26.7% PD. Patients CR had improved as measured HVLT-R Total Recall (p=0.0005), Delayed (p=0.0003), Recognition (p=0.011), TMT-B (p=0.033), COWA (p=0.016), Clinical Trial Battery Composite score (p=0.0011). Multivariable analysis demonstrated less deterioration (p=0.019) PR (p=0.0086) SD/PD (p=0.031) SD/PD. CONCLUSIONS result similar 6-months. associated better preservation. This suggests investigation into treatment escalation may provide further benefit along memantine.Grant support from NCI-UG1CA189867 U24CA180803.