Tumor M2 pyruvate kinase: a tumor marker and its clinical application in gastrointestinal malignancy

Proliferating cells, in particular tumor cells, express a dimeric isoenzyme of pyruvate kinase, termed Tumor M2 pyruvate kinase. In the last few years, much attention has been paid to this novel tumor marker that can be determined in EDTA-plasma and in the feces. It has been used in diagnosis and surveillance of a variety of malignant diseases. As compared with the established tumor markers, Tumor M2-PK in EDTA-plasma proves to have at least equal sensitivity in pancreatic, gastric, esophageal, colorectal and cholangiocellular cancer. In combination with established tumor markers, EDTA-plasma M2-PK is a useful tool in diagnosis and surveillance of gastrointestinal tumors. In colorectal cancer, M2-PK in EDTA-plasma even proves superiority as compared with CEA. Fecal Tumor M2-PK testing resembles a good noninvasive screening parameter for colorectal cancer with a reported sensitivity of 68.8-91.0% and a specificity of 71.9-100%. It is superior to fecal occult blood testing in colorectal cancer screening. Since it is effective, easy to handle and bears rather low costs, fecal Tumor M2-PK testing is recommended for large-scale CRC screening.