Cancer biomarkers include risk factors like genes (BRCA1/2, Bcrl-Abl), including genes with frequently occurring mutations (KRAS G12C), proteins (e.g. cancer antigens, like CA-125 and YKL-40), and metabolites. Metabolites are a critical biomarker, because cancer cells change from normal respiration (oxidative phosphorylation) to abnormal burning of calories (glycolysis). The excess of glycolysis can be detected using a glucose analogue (fluorine-18-fluorodeoxyglucose, 18F-FDG) that can be detected using positron emission tomography (PET).