Tumor markers are biomarkers that can be found in blood, urine or different body tissues, produced either by cancer cells or normal cells in response to cancer or in different noncancerous conditions (gastrointestinal stromal tumors). Their use varies from cancer screening on a population basis, to staging different tumors or to evaluate the efficiency of the treatment. Most frequently used in gastrointestinal malignancies are: carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9 and αfetoprotein. However there are many markers that can be useful in dealing with gastrointestinal cancer such as: carbohydrate antigen 125, cyfra 21-1, chromogranin, tumor M2-PK, neuron-specific enolase, smooth muscle actin [1]. Future research show the utility of multiple tumor marker test, when by combining more tests in parallel the predictive value might be increased. For example: when talking about pancreatic or stomach cancer one might combine: CEA, CA19-9 and CA 72-4 [1, 2].