AIM: Tumor formation is generally linked to an expansionof glycolytic phosphometabolite pools and aerobic glycolyticflux rates.To achieve this,tumor cells generally overexpressa special glycolytic isoenzyme,termed pyruvate kinase typeM_2.The present study was designed to evaluate the useof a new tumor marker,tumor M_2-PK,in discriminatinggastrointestinal cancer patients from healthy controls,andto compare with the reference tumor markers CEA andCA72-4.METHODS: The concentration of tumor M2-PK in body fluidscould be quantitatively determined by a commerciallyavailable enzyme-linked immunosorbent assay (ELISA)-kit(ScheBo(?) Tech,Giessen,Germany).By using this kit,thetumor M_2-PK concentration was measured in EDTA-plasmaof 108 patients.For the healthy blood donors a cut-offvalue of 15 U/mL was evaluated,which corresponded to90% specificity.Overall 108 patients were included in thisstudy,54 patients had a histological confirmed gastriccancer,54 patients colorectal cancer,and 20 healthyvolunteers served as controls.RESULTS: The cut-off value to discriminate patients fromcontrols was established at 15 U/mL for tumor M_2-PK.Themean tumor M_2-PK concentration of gastric cancer was26.937 U/mL.According to the TNM stage system,the meantumor M_2-PK concentration of stage Ⅰ was 16.324 U/mL,ofstage Ⅱ 15.290 U/mL,of stage Ⅲ 30.289 U/mL,of stage Ⅳ127.31 U/mL,of non-metastasis 12.854 U/mL and of metastasis35.711 U/mL.The mean Tumor M_2-PK concentration ofcolorectal cancer was 30.588 U/mL.According to the Dukesstage system,the mean tumor M_2-PK concentration ofDukes A was 16.638 U/mL,of Dukes B 22.070 U/mL,andof Dukes C 48.024 U/mL,of non-metastasis 19.501 U/mL,ofmetastasis 49.437 U/mE The mean tumor M_2-PK concentrationallowed a significant discrimination of colorectal cancers(30.588 U/mL) from controls (10.965 U/mL) (P<0.01),andgastric cancer (26.937 U/mL) from controls (10.965 U/mL)(P<0.05).The overall sensitivity of tumor M_2-PK for colorectalcancer was 68.52%,while that of CEA was 43.12%.Ingastric cancer,tumor M_2-PK showed a high sensitivity of50.47%,while CA72-4 showed a sensitivity of 35.37%. CONCLUSION: Tumor M_2-PK has a higher sensitivity thanmarkers CEA and CA72-4,and is a valuable tumor markerfor the detection of gastrointestinal cancer. AIM: Tumor formation is generally linked to an expansion of glycolytic phosphometabolite pools and aerobic glycolytic flux rates. To achieve this, tumor cells generally overexpressa special glycolytic isoenzyme, termed pyruvate kinase type M_2.The present study was designed to evaluate the use of a new tumor marker, tumor M_2-PK, in discriminating gastrointestinal cancer patients from healthy controls, and compare with the reference tumor markers CEA and CA72-4. METHODS: The concentration of tumor M2-PK in body fluid scientifically quantified determined by a commercially available enzyme-linked immunosorbent assay (ELISA) -kit (ScheBo (?) Tech, Giessen, Germany) .By using this kit, the tumor M_2-PK concentration was measured in EDTA-plasmaof 108 patients. For the healthy blood donors a cut-off value of 15 U / mL was evaluated, Of the 108 patients were included in this study, 54 patients had a histological confirmed gastriccancer, 54 patients colorectal cancer, and 20 healthyvolu The cut-off value to discriminate patients from controls was established at 15 U / mL for tumor M_2-PK. The capacity of the tumor M_2-PK concentration of gastric cancer was 26.937 U / mL. According to the TNM stage system, the mg of Mg2-PK concentration of stage I was 16.324 U / mL, of stage II 15.290 U / mL, of stage III 30.289 U / mL, of stage IV 127.31 U / mL, of non-metastasis 12.854 U / mL and of metastasis 35.711 U / mL. The mean Tumor M 2 -PK concentration of colorectal cancer was 30.588 U / mL. According to the Dukesstage system, the mean tumor M_2-PK concentration of Dukes A was 16.638 U / mL, of Dukes B 22.070 U / mL and of Dukes C 48.024 U / mL, of non-metastasis 19.501 U / mL, ofmetastasis 49.437 U / mE The mean tumor M_2-PK concentrationallowed a significant discrimination of colorectal cancers (30.588 U / mL) from controls (10.965 U / mL (P <0.05). The overall sensitivity of tumor M_2-PK for colorectal cancer was 68.52%, while that of CEAwas 43.12% .Ingastric cancer, tumor M_2-PK showed a high sensitivity of 50.47% while CA72-4 showed a sensitivity of 35.37%. CONCLUSION: Tumor M_2-PK has a higher sensitivity thanmarkers CEA and CA72-4, and is a valuable tumor marker for the detection of gastrointestinal cancer.