 Studies from various international working groups have revealed a significantly increased amount of Tumor M2-PK in EDTA-plasma samples of patients with renal, lung, breast, cervical and gastrointestinal tumors (oesophagus, stomach, pancreas, colon, rectum), as well as melanoma, which correlated with the tumor stage.The combination of Tumor M2-PK with the appropriate classical tumor marker, such as CEA for bowel cancer, CA 19-9 for pancreatic cancer and CA 72-4 for gastric cancer, significantly increases the sensitivity to detect various cancers.An important application of the Tumor M2-PK test in EDTA-plasma is for follow-up during tumor therapy, to monitor the success or failure of the chosen treatment, as well as predicting the chances of a “cure” and survival.