Transgender individuals are underrepresented in neuro-oncology research. Little is known regarding the impact of GAHT on CNS tumor outcomes. 

Twelve patients (median age 29; sex assigned at birth: 8 male, 4 female) with glioblastoma (n=1), IDH-mutant astrocytoma (n=2), oligodendroglioma (n=2), ependymal tumors (n=2), pituitary adenoma (n=2), NF2-associated schwannoma/meningioma (n=1), and diffuse glioma with BRAF-V600E mutation (n=1) were included. Eight received feminizing GAHT (estrogen) and four masculinizing GAHT (testosterone). .  

Tumor-directed treatments included surgery (n=10), radiation therapy (n=6), and systemic therapy (n=7, using temozolomide, lomustine, ivosidenib, vorasidenib, lapatinib, bevacizumab). No increase in tumor treatment-related adverse events attributable to GAHT use were noted.. 

Six patients initiated feminizing GAHT before tumor diagnosis (median exposure 32 months, range:13-50) and continued GAHT after tumor identification. Within this group, only one patient with glioblastoma experienced tumor progression during follow up.  

Six patients started GAHT after tumor diagnosis (2 feminizing, 4 masculinizing). One patient with NF2 developed compressive optic neuropathy related to a right sphenoid wing meningioma after four years of GAHT (oral estrogen 4 mg daily). Vision improved with treatment discontinuation. Estrogen rechallenge led to recurrence of vision symptoms, prompting discontinuation. One patient with oligodendroglioma had tumor recurrence 12 years after diagnosis and 4 years after GAHT initiation. Remaining 4 patients did not experience recurrence with a median GAHT exposure of 29 months (range: 2-85).