This study assesses the prevalence of dormancy periods before and after resection in IDH-mutant gliomas managed without anti-cancer or adjuvant therapy.

The natural history of isocitrate dehydrogenase (IDH)-mutant gliomas remains understudied in the post-IDH era. While existing paradigms assume continuous linear growth, our clinical observations suggest saltatory progression with periods of dormancy. Knowledge of growth patterns may have significant implications for treatment timing.

We conducted a retrospective analysis of a single physician’s cohort of adults with pathologically confirmed IDH-mutant gliomas followed in a neuro-oncology clinic from 2019 to 2025. Patients were included if they had ≥1 year of serial surveillance brain MRI before and/or after surgical intervention and received no adjuvant therapy. Tumor growth was assessed using manual 2D linear measurements on serial T2-fluid attenuated inversion recovery (FLAIR) axial sequences. Dormancy was defined as <2 mm growth over at least one year. Volumetric segmentation of FLAIR and T2 axial sequences was also performed in InteleViewer and 3D Slicer with an experienced neuroradiologist to validate and refine 2D findings.

Our 2D analysis identified the prevalence of dormancy both pre-resection and post-resection. In the pre-resection cohort (n=3), two astrocytomas demonstrated dormancy durations of 15 and 120 months, and one oligodendroglioma showed continuous growth. Among post-resection patients (n=10), 80% exhibited at least one dormancy period. Oligodendrogliomas had a median dormancy duration of >36 months. Astrocytomas showed more variable growth, with half exhibiting dormancy and half continuous growth. Overall, heterogeneity in growth patterns was observed, with periods of stability interspersed with slow progression. Volumetric analysis is ongoing and will enhance the precision of these findings.