Predictors of Time-to-recurrence in High-grade Glioma: A Multi-institutional Retrospective Analysis

Introduction: Previous studies have shown that there is a higher incidence of glioblastoma in non-Hispanic White patients. However, the literature is mixed on the presence of racial disparities in high-grade glioma (HGG), especially with respect to tumor genetics. The goal of this study is to better understand how race and IDH status relate to the rate of recurrence in HGG.

Methods: This is a retrospective study of patients treated at three institutions between 2015 and 2020. To be included, patients were adults, had pathology-confirmed HGG, and were followed throughout the entire course of their illness. Demographic factors, IDH1 mutation status, MGMT methylation, medical management, functional status, and extent of surgical resection were recorded. Recurrences were defined according to the RANO 2.0 criteria. Mann-Whitney U tests, Fisher’s exact tests, and Cox proportional regression were performed.

Results: Among the 121 patients, 14 (11.6%) were IDH1 mutant. Of these patients 52.9% were White, 12.4% were Black, 6.6% were Asian, 21.5% identified as a different race, and 7.4% had no race available. Patients with IDH1 mutant HGG were on average 16.4 years younger (p < 0.0001). Patients with glioblastoma were more likely to be White (p=0.0202). There were no statistically significant differences in management of patients based on race or tumor genetics. Multivariate analysis using IDH1 status, race, and age showed two significant predictors of time-to-recurrence: IDH1 wildtype tumors had an estimated effect of recurring in 6.04 months (SEM 92 days; p = 0.0491), and Black race had an estimated effect of recurring in 7.29 months (SEM 96 days; p = 0.0238).

Conclusion : White patients were more likely to have glioblastoma. IDH1 status, as expected, was a strong, independent predictor of time to recurrence. However, White race, independent from IDH1, did not predict time-to-recurrence. Black race, independent from IDH1, was a strong predictor of time-to-recurrence.