Introduction: Glioblastoma (GBM) is a highly lethal brain tumor with a median survival of less than two years. Residual enhancing tumor volume (RETV) after surgery has been shown to be a better predictor of overall survival (OS), compared to extent of resection (EOR) for newly-diagnosed GBM, but the role of RETV versus EOR in predicting OS has yet to be elucidated in recurrent GBM.
Methods: This is an IRB-approved retrospective chart review that included volumetric analysis of peri-operative MRIs to evaluate predictors of OS in recurrent GBM.
Results: 43 consecutive patients who underwent surgery for recurrent GBM were identified. Median age at diagnosis was 59 years. Median Karnofsky Performance Score at diagnosis was 90, and it was found to be a significant predictor of survival (p = 0.0214). Median preoperative tumor volume at recurrence was 26.909cm3 while median RETV was 0.894cm3. Median EOR was 94.5%. 48% of patients had intraoperative MRI (iMRI) used for their recurrent resection. Median RETV in patients with iMRI was 0.451cm3 (IQR: 0, 1.095), while median RETV in patients without iMRI was 3.512cm3 (IQR: 0, 5.709); these were significantly different (p = 0.0388). Median OS from the date of recurrent resection was 11.9 months. RETV and EOR were not found to be significant predictors of OS in the full population; however RETV was associated with OS in patients who did not have iMRIs (p = 0.0077), while EOR was not.
Conclusions: After adjusting for use of iMRI, RETV was a better predictor of OS than EOR. Remarkably, the use of iMRI consistently produced minimal RETVs to the point where other variables became drivers of OS. Unless functional considerations are present, complete or near complete removal of enhancing tumor should be considered standard of care in recurrent GBM.
Patient Care: By showing that lower residual enhancing tumor volume is a better predictor of overall survival than extent of resection in patients with recurrent glioblastoma, this research emphasizes the importance of complete or near complete removal of enhancing tumor. This research also demonstrates how intraoperative MRI produces minimal residual enhancing tumor volumes, and this will hopefully improve patient care by placing an emphasis on the use of intraoperative imaging/visualization to help achieve lowest possible residual enhancing tumor volumes.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the role of residual enhancing tumor volume in predicting overall survival after resection of recurrent glioblastoma in comparison to extent of resection
2) Discuss the role of intraoperative MRI in complete or near complete removal of recurrent glioblastoma