Pilot Study of Liquid Biopsy as a Diagnostic Tool for Gliomas by Analyzing Circulating Tumor DNA in Blood Samples, and Its Validation With the Corresponding Tissue Biopsies.

Currently, brain tumors are detected by means of an imaging technique (usually magnetic resonance imaging) with a contrast agent. The determination of the type of tumor, as well as its grading, is usually done subsequently with a biopsy of the tissue, where different solid samples are extracted as representative as possible to analyze them in the Pathological Anatomy service. Nevertheless, there are some factors that limit surgical access, such as: the advanced age of the patient, the location of the tumor in eloquent or risky areas, as well as the presence of large tumors with very diffuse borders. In these cases, the diagnosis of the brain tumor is usually made directly with the magnetic resonance image, which implies a risk of error due to the lack of clinical information from this test.

Limitations like these make the minimally invasive procedure of liquid biopsy an extremely necessary diagnostic tool. For this reason, the investigators want to start a pilot study of this technique in those patients with brain lesions in the resonance images compatible with a glioma-like tumor.

In particular, the main aim of the study is to analyze the blood samples obtained from these patients in order to detect and quantify the circulating DNA (ctDNA) of tumor cells on it. These DNA fragments are expelled into the bloodstream by mechanisms still unknown as a result of numerous processes of apoptosis and necrosis of tumor cells. By analyzing them through a ddPCR, the investigators will try to detect the specific mutations present in this tumoral ctDNA, allowing the team to confirm the presence of a glioma-type tumor, and providing real-time information of its classification as astrocytoma or oligodendroglioma.