The general objective of this project is to evaluate the value of cell-free DNA circulating in plasma as a marker of tumor evolution in patients with high-grade gliomas and meningiomas.

To this end, we propose to longitudinally collect four samples of plasma at the following time points:

• T0: before surgery;
• T1: one month after surgery;
• T2: one month after the end of radiotherapy;
• T3 at the time of radiological progression.

The goal is to evaluate whether changes in plasma concentration of circulating cell-free DNA can help predict progression-free survival, overall survival, and response to therapies.

Inclusion Criteria:

• Age ≥ 18 years
• Finding, on an MRI scan of the brain with gadolinium, of a brain lesion compatible with a primary brain tumor, intra- or extra-axial, suspected for a high-grade glioma or a high-grade meningioma, manifested with new onset neurological symptoms
• Clinical indication to perform a biopsy or surgical resection of the lesion
• Karnofsky Performance Status (KPS) ≥ 60
• Signature of informed consent

Exclusion Criteria:

• Absolute contraindications to magnetic resonance imaging or to the administration of gadolinium (e.g. patients with pacemakers or other non-magneto-compatible devices)
• Known positivity for HIV, HCV or HBV
• There are clinical, biological or instrumental data suggesting that the brain lesion is non-neoplastic in nature (e.g., abscess, vascular malformation, inflammatory disease of the Central Nervous System)
• Women who are pregnant or breastfeeding

The study population will consist of adult patients with a newly diagnosed brain lesion compatible with high-grade glioma or high-grade meningioma, for whom a brain biopsy or exeresis has been indicated. Patients of both sexes, aged between 18 and 85 years-old, with a Karnofsky Performance Status (KPS)≥ 60 will be enrolled.