Plasma glutamate–a prognostic marker of cancer and of other immunodeficiency syndromes?

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Abstract
Elevated plasma levels of glutamate (GLU) have been reported to occur in patients with malignancies and other immunodeficiency syndromes (IDS). To evaluate, whether GLU is useful as prognostic indicator, the plasma concentrations were determined in patients with colorectal carcinoma (CRC), with breast cancer (BRC), and with HIV-infection (HIV). The results were correlated with the disease-stages, and compared with data obtained from patients with benign diseases of the same organ, as well as from sex-matched healthy volunteers. GLU concentrations (volunteers: 27.4+17.6 μmol/1) were elevated in all BRC patients (range of mean values: 53.5-83.2 umol/1), in CRC patients with T2-T4-tumours (means: 46.8-85.9), and in HIV+ patients of stage WR 5, 6 (means: 53.9-69.7 μmol/1). All CRC- and BRC-patients with metastases showed highly significant elevations of GLU concentrations (p<0.001), but there were no direct correlations between disease stages and GLU levels. Pre-operative patients with benign diseases (diverticulitis, adenoma=GID; and mastopathy=MTP) showed increased GLU levels, which were comparable to those of the tumour patients. The glutamine/GLU ratios (volunteers: 19.3±15.0) were decreased only in HIV-WR 6 (7.6±2.1), and BRC-stage 4 (8.0±1.7). From these results we deduce that the plasma GLU concentrations do not allow a discrimination either between patients with malignancies and without, and between persons of different disease stages.