Treatment and outcomes of IDH1-mutant gliomas in elderly patients

Isocitrate dehydrogenase (IDH) mutations in both high- and low-grade gliomas are associated with an increase in survival compared with IDH-wild-type (IDHwt) tumors. A rare and understudied population is elderly individuals, ≥ 65 years of age, who have IDH1-R132H-mutant (IDHmt) gliomas. The objective of this paper was to characterize the institutions' experience with IDHmt gliomas in a patient population ≥ 65 years of age over the last 10 years.

A retrospective study of individuals ≥ 65 years of age with IDHmt gliomas treated between 2010 and 2020 at Memorial Sloan Kettering was performed.

Twenty-five patients ≥ 65 years of age underwent resection or biopsy with a diagnosis of IDHmt glioma (52% WHO grade II, 32% WHO grade III, and 16% WHO grade IV). The most common presenting symptoms were seizure (28%) and motor or sensory deficits (24%). On preoperative MRI, 56% of tumors demonstrated contrast enhancement and 44% had no enhancement. Most patients underwent craniotomy for resection (n = 23, 92%), with subtotal resection achieved in the majority (16/23, 69.6%). Postoperative discharge location included home (64%), acute rehabilitation (16%), subacute rehabilitation (8%), and unknown (12%). Most patients received postoperative chemotherapy (72%) and radiation therapy (68%). The 2- and 5-year survival rates for the overall cohort were 83.1% (95% CI 69.3%-99.7%) and 69.7% (95% CI 53.2%-91.3%), respectively, with gross-total resection or near-total resection, contrast enhancement, and WHO grade significantly associated with survival. From the clinical sequencing data, no significant differences were identified between younger and older IDHmt cohorts.

While IDH mutation in elderly patients may be rare, these patients have favorable survival relative to their IDHwt counterparts. Age at diagnosis should not be used in isolation to suggest a molecular IDHwt status or poor prognosis when guiding patient treatment decisions.