The feasibility of using this method in patients with breast cancer has been demonstrated recently (12): Higher Lac/Pyr ratios were observed in larger and more aggressive tumors (including all triple-negative cancers), and this correlated with the expression of the plasma membrane transporter mediating uptake of pyruvate into tumor cells (monocarboxylate transporter 1) and hypoxia-inducible factor 1-α. This evidence concerns the gene SLC16A1 and breast cancer.