In this paper, we used a different analytical technology (ultrasensitive electroluminescent immunoassay instead of PEA) and an independent, more diverse, and larger cohort of patients, to validate GFAP, NEFL, matrix metalloprotease 3 (MMP3) and fatty acid-binding protein 4 (FABP4), as non-invasive biomarkers of benign and malignant primary and secondary brain tumors. The gene discussed is GFAP; the disease is brain neoplasm.