Metabolic Marker GLUT1 in Salivary Gland Cancers: Quantification and Effect-Size Estimation

Background: Glucose transporter 1 (GLUT1) is frequently upregulated in solid tumors and may reflect metabolic adaptation of malignant tissues. However, evidence regarding GLUT1 protein levels in salivary gland tumors remains limited. Methods: In this pilot study, GLUT1 protein concentrations were quantified in tissue homogenate supernatants from salivary gland tumors (n = 9) and non-malignant salivary gland tissue obtained from surgical margins (controls; n = 4) using a commercial ELISA kit (BlueGene Biotech; E01G0020) according to the manufacturer's instructions. Supernatants were stored at -80 °C until analysis. Group comparisons were performed using a non-parametric Mann-Whitney U test. Results: GLUT1 levels showed substantial inter-individual variability. The tumor group exhibited higher values than controls [median (IQR): 15.53 (12.44-26.38) vs. 10.14 (7.40-13.26); mean ± SD: 19.26 ± 11.49 vs. 10.33 ± 4.39 (ng/mL)], although the between-group difference did not reach statistical significance (Mann-Whitney U = 27, two-sided p = 0.199). Conclusions: These preliminary data suggest heterogeneity of GLUT1 levels in salivary gland tumor tissue homogenates and numerically higher concentrations compared with non-malignant margin tissue. These findings should be interpreted as preliminary and hypothesis-generating. Larger, clinically annotated cohorts with orthogonal validation are required before any diagnostic, prognostic, or clinical relevance of GLUT1 can be considered.