Isocitrate-dehydrogenase-mutant lower grade glioma in elderly patients: treatment and outcome in a molecularly characterized contemporary cohort

Abstract

Purpose: Lower-grade glioma (LGG) is rare among patients above the age of 60 (“elderly”). Previous studies reported poor outcome, likely due to the inclusion of isocitrate dehydrogenase (IDH) wildtype astrocytomas and advocated defensive surgical and adjuvant treatment. This study set out to question this paradigm analyzing a contemporary cohort of patients with IDH mutant astrocytoma and oligodendroglioma WHO grade 2 and 3. Methods: Elderly patients treated in our department for a supratentorial, hemispheric LGG between 2009 and 2019 were retrospectively analyzed for patient-, tumor- and treatment-related factors and progression-free survival (PFS) and compared to patients aged under 60. Inclusion required the availability of subtype-defining molecular data and pre- and post-operative tumor volumes. Results: 207 patients were included, among those 21 elderlies (10%). PFS was comparable between elderly and younger patients (46 vs. 54 months; p = 0.634). Oligodendroglioma was more common in the elderly (76% vs. 46%; p = 0.011). Most patients underwent tumor resection (elderly: 81% vs. younger: 91%; p = 0.246) yielding comparable residual tumor volumes (elderly: 7.8 cm3; younger: 4.1 cm3; p = 0.137). Adjuvant treatment was administered in 76% of elderly and 61% of younger patients (p = 0.163). Uni- and multi-variate survival analyses identified a tumor crossing the midline, surgical strategy, and pre- and post-operative tumor volumes as prognostic factors. Conclusion: Elderly patients constitute a small fraction of molecularly characterized LGGs. In contrast to previous reports, favorable surgical and survival outcomes were achieved in our series comparable to those of younger patients. Thus, intensified treatment including maximal safe resection should be advocated in elderly patients whenever feasible.