QOL-23. BASELINE TOTAL BRAIN VOLUME PREDICTS FOR POORER QOL AND REDUCED OVERALL SURVIVAL AFTER CRANIAL RADIOTHERAPY IN OLDER PATIENTS WITH GLIOBLASTOMA (GBM): RESULTS FROM THE PROSPECTIVE BRITER STUDY

Abstract

Abstract GBM incidence peaks in the 7th and 8th decades of life with prognosis worsening with age. Short-course partial brain radiotherapy, +/- chemotherapy, extends survival but there is no validated evidence for prediction of individual risk of acute radiotherapy related side effects. BRITER, a prospective multicentre observational trial, recruited patients with newly diagnosed GBM aged ≥ 65 planned for cranial radiotherapy. Baseline MRI scans were analysed for 5 putative markers of brain resilience including relative total brain volume (ratio of cerebrospinal fluid (CSF) volume to total intracranial volume (TIV)) and their relationship to change in QoL. 126 patients were enrolled; mean age 72 years (range 65-83); 67% men, 33% women. 4% had a radiological diagnosis, 19% biopsy and 77% had debulking surgery. 21% received palliative radiotherapy alone (25% 30Gy/6#, 75% 40Gy/15#), 79% received radiotherapy with concurrent TMZ (47% 40Gy/15#, 53% 60Gy/30#). Median OS was 11.3 months. After accounting for age, sex, treatment and baseline MoCA score, there was a significant relationship between baseline CSF:TIV ratio and change in QoL score at 8 weeks post treatment. For each unit point of increase in CSF:TIV ratio, there was a corresponding decrease in EORTC QLC C30 QoL score by a factor of 1.27 (coefficient -1.27, 95% CI -3.24 to -0.19 p = 0.02). 35 participants were too unwell to complete questionnaires or had died by the 8 week follow up visit. In this subgroup, post hoc logistic regression showed baseline CSF:TIV ratio was related to risk of non-attendance (OR 1.35, 95% CI 1.01-1.80, p = 0.04). Cox regression models were fitted for time to death in 88 participants who had analysable baseline MRI sequences. Baseline CSF:TIV was associated with worsened OS (HR 1.41, 95% CI 1.19-1.66, p < 0.001). This unique prospective study indicates that baseline imaging parameters can predict the impact of cranial radiotherapy on QoL and OS.