This prospective multicenter study aims to enroll GBM patients who will undergo repeated assessments (preoperatively and 3 months post-surgery) to detect circulating tumor cells and analyze the transcriptomic profiles of EVs in their blood. The prognostic and monitoring significance of these biomarkers to disease course (assessing treatment efficacy, resistance incidence, tumor progression) will be evaluated. Concurrently, proteomic profiles typical of GBM will be analyzed in blood and ocular secretion samples from GBM patients, patients with low-grade gliomas, and patients without brain tumors to identify and validate novel protein biomarkers suitable for disease monitoring. Additionally, this study proposes an innovative approach to monitor GBM patients by investigating the presence of GBM-specific nucleic acid fragments in urine.