Colorectal cancer (CRC) can be cured in most cases if diagnosed at an early stage. Carcinoembryonic antigen (CEA) remains the most widely used cancer marker for determining prognosis of CRC. Previous studies have shown that plasmatic tumor M2 pyruvate kinase (Tu M2-PK) is highly sensitive in CRC detection at an early stage and equally as good as the results for established tumor markers with clinical potential for cancer prognosis and monitoring. The aim of this study was to assess the prognostic value of Tu M2-PK in plasma using a survival analysis in combination with CEA in serum in patients newly diagnosed with CRC. The initial study included 183 patients who had a complete diagnostic colonoscopy. This cohort study was designed to evaluate the survival in patients with histologically confirmed gastrointestinal cancers (n = 41). Tu M2-PK concentrations in EDTA plasma were determined immunologically using an ELISA assay. Plasma Tu M2-PK levels were significantly higher in patients with distant metastases, stage IV for TNM score, and advanced stage (C+D) subgroups of Dukes than other subgroups. The univariate Cox's analysis showed that CEA and Tu M2-PK gave high hazard ratios for risk of death (odds ratio CEA = 3.57 and odds ratioTu M2-PK = 2.23) and comparable values in average survival time. The results for both biomarkers did not overlap. These findings suggest that plasmatic Tu M2-PK levels of more than 20 U/mL may be a predictor of death risk.