Introduction: Isocitrate dehydrogenase I (IDH1) mutant glioblastomas (GBM) have been shown to respond more favorably to gross total resection (GTR). The role of intra-operative magnetic resonance imaging (iMRI) in the resection of IDH-1 mutant GBMs has not been studied. This study aimed to assess impact of iMRI on isocitrate-dehydrogenase-1 (IDH-1) mutant GBMs
Methods: A multicenter database (2009-2018) identified newly diagnosed IDH-1 mutant glioblastomas. Kaplan-Meier analysis assessed overall survival (OS) and progression-free survival (PFS) and logistic regression was performed to calculate odds of GTR determinations. American Society of Anesthesiology (ASA) scores were used as surrogate for performance status. iMRI was performed using a movable ceiling-mounted high-field magnet at operating surgeon’s preference.
Results: IDH-1 status was available for 428 resected newly diagnosed glioblastomas, 33 were mutated, and 29 resected). Overall, IDH-1 mutants had improved OS (14.93 versus 31.47 months, p=.003), and PFS (10.10 versus 23.43 months, p=.007) compared to wildtype cases. In 29 patients with IDH-1 mutations, use of iMRI trended towards improved OS from 14.67 (n=8, non-iMRI) to 58.47 months (n= 21, iMRI, p=.09; HR 0.342 [0.093, 1.251]), led to increased PFS (7.70 to 24.43 months, p=.008; HR 0.145 [0.028, 0.737]), and to higher rates of GTR (6/20, compared to 0/7 in the non-iMRI group, 2 unknown). IDH-1 status was not an independent predictor of GTR (p=.67, OR = 1.306 [0.389, 4.381]) after controlling for age, ASA, and iMRI. iMRI was an independent predictor of GTR after controlling for age, ASA, and IDH-1 (p=.02, OR 2.637 [1.174, 5.927]).
Conclusions: The use of iMRI during resection for IDH-1 mutant glioblastomas led to increased PFS, and a strong trend toward increased OS in comparison to non-iMRI cases. IDH1 status is not an independent predictor of achieving GTR. iMRI may be of particular benefit in IDH1 mutants due to improved extent of resection.
Patient Care: iMRI is a relatively novel surgical adjunct that is gaining further adoption. Identifying subsets of patients, such as IDH-1 mutants, that are particularly amenable to GTR will allow targeted utilization of this technique.
Learning Objectives: By the conclusion of this session, participants should be able to describe the impact of IDH-1 mutations on survivorship in glioblastoma, 2) describe the role of iMRI in the surgical treatment of IDH-1 mutant GBMs, and 3) discuss extent of resection in IDH-1 mutant tumors.