NCOG-02. PRETREATMENT VOLUME OF MRI-DETERMINED WHITE MATTER INJURY (WMI) PREDICTS COGNITIVE DECLINE AFTER HIPPOCAMPAL AVOIDANT (HA) WBRT FOR BRAIN METASTASES: SECONDARY ANALYSIS OF NRG ONCOLOGY RTOG 0933
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Abstract
PURPOSE
RTOG 0933 demonstrated benefits to memory following HA-WBRT, supporting the hypothesis of hippocampal radiosensitivity and associated memory specificity. However, some patients demonstrated cognitive decline, suggesting mechanisms outside hippocampal radiosensitivity playing a role. WMI has been implicated in RT-induced cognitive decline. This secondary analysis explored the relationship between pre-treatment WMI and memory following HA-WBRT.
METHODS
113 patients received HA-WBRT. Standardized cognitive assessments were performed at baseline, 2, 4, and 6 months. The primary endpoint was Hopkins Verbal Learning Test Delayed Recall (HVLT-DR) at 4 mos. Secondary endpoints included HVLT Total Recall (HVLT-TR) and Recognition (HVLT-Recog). Of 113 patients, 34 underwent pre-treatment and 4-month post-treatment HVLT testing and pre-treatment post-contrast volumetric T1 and axial T2/FLAIR MRI. Volumetric analysis of metastatic disease burden and disease-unrelated WMI was conducted on the pre-treatment MRI. Correlational analyses were performed examining the relationship between pre-treatment WMI and HVLT outcomes following HA-WBRT.
RESULTS
Correlation was found between larger volumes of pre-treatment WMI and decline in HVLT-Recog (r=.54, p<.05) and a correlational trend was observed between larger volume of pre-treatment WMI and decline in HVLT-DR (r=.31, p=.08). Patients with higher pre-treatment disease burden experienced a greater magnitude of stability/positive shift in HVLT-TR and HVLT–DR following HA-WBRT. (r=-.36 and r=-.36, p’s <.05), compared to the magnitude of stability/positive shift in those with lesser disease burden.
CONCLUSION
In patients receiving HA-WBRT, pre-treatment WMI predicts memory decline, suggesting white matter integrity pre-treatment contributes to the pathogenesis of post-WBRT cognitive toxicity independent of hippocampal stem cell radiosensitivity. Less decline/improvement in HVLT following HA-WBRT for patients with higher pre-treatment intracranial metastatic burden supports the importance of WBRT-induced intracranial control on cognition. These imaging biomarkers for cognitive toxicity will be further explored on NRG CC001 and CC003, phase III trials of WBRT with or without HA. Supporting NCI grants: U10CA180868, U10CA180822, U24CA180803, UG1CA189867.
