Elevated Lactate and Total Protein Levels in Stereotactic Brain Biopsy Specimen; Potential Biomarkers of Malignancy and Poor Prognosis

Cancer cells bear various metabolic alterations in order to survive and progress. Neoplastic cells rewire their metabolic pathways for fermentation of glucose and production of more lactate. Microenvironment acidification is a common feature of many neoplastic lesions. In other words, most cancer cells produce energy ineffectively, by aerobic glycolysis, considered as "Warburg effect". Mounting on previous evidence, hypoxia also induces tumor stemness, diminished apoptosis, and more invasive behavior as well as angiogenesis. In this study, we aimed to investigate whether more lactate concentration in stereotactic puncture specimen of various brain lesions can be an alarming sign of malignancy and higher grades. The current study aims at providing a rapid prognostic biomarker of higher grades for cystic brain lesions approached stereotactically before the complete pathologic grading report is prepared.

We investigated the biochemical cyst content of 44 patients with astrocytomas, 8 craniopharyngiomas, 1 oligodendroglioma and 2 cases with metastatic lesions after stereotactic surgery (47 patients were enrolled in the study). Cyst fluid was analyzed for pH, total protein concentration, cytology, and lactate. The association of these parameters was explored relative to tumor behavior (e.g., tumor grade, type, and cyst progression). The current study was conducted at Firoozgar hospital, Tehran, Iran. Patients were followed for any possible progression from 2014 to 2017.

The analyses revealed a significant and positive correlation between grade and lactate concentration (P≤0.001); as well as between grade and mean total protein concentration (P = 0.046). This suggests that more lactate and total protein concentration in stereotactic specimen can be an alarming sign of higher grades and poor outcome in astrocytoma cysts. However, craniopharyngiomas; as benign lesions; had significantly lower lactate (P≤0.001) and total protein concentrations (P = 0.018) than astrocytomas.

Higher total protein and lactate concentrations in the stereotactic biopsy specimens are alarming signs of poor outcome and higher grades in astrocytomas.