Published online Jun 1, 2004. doi: 10.3748/wjg.v10.i11.1643
Revised: October 4, 2003
Accepted: October 7, 2003
Published online: June 1, 2004
AIM: Tumor formation is generally linked to an expansion of glycolytic phosphometabolite pools and aerobic glycolytic flux rates. To achieve this, tumor cells generally overexpress a special glycolytic isoenzyme, termed pyruvate kinase type M2. The present study was designed to evaluate the use of a new tumor marker, tumor M2-PK, in discriminating gastrointestinal cancer patients from healthy controls, and to compare with the reference tumor markers CEA and CA72-4.
METHODS: The concentration of tumor M2-PK in body fluids could be quantitatively determined by a commercially available enzyme-linked immunosorbent assay (ELISA) -kit (ScheBo® Tech, Giessen, Germany). By using this kit, the tumor M2-PK concentration was measured in EDTA-plasma of 108 patients. For the healthy blood donors a cut-off value of 15 U/mL was evaluated, which corresponded to 90% specificity. Overall 108 patients were included in this study, 54 patients had a histological confirmed gastric cancer, 54 patients colorectal cancer, and 20 healthy volunteers served as controls.
RESULTS: The cut-off value to discriminate patients from controls was established at 15 U/mL for tumor M2-PK. The mean tumor M2-PK concentration of gastric cancer was 26.937 U/mL. According to the TNM stage system, the mean tumor M2-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 M2-PK concentration of colorectal cancer was 30.588 U/mL. According to the Dukes stage system, the mean tumor M2-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, of metastasis 49.437 U/mL. The mean tumor M2-PK concentration allowed a significant discrimination of colorectal cancers (30.588 U/mL) from controls (10.965 U/mL) (P < 0.01), and gastric cancer (26.937 U/mL) from controls (10.965 U/mL) (P < 0.05). The overall sensitivity of tumor M2-PK for colorectal cancer was 68.52%, while that of CEA was 43.12%. In gastric cancer, tumor M2-PK showed a high sensitivity of 50.47%, while CA72-4 showed a sensitivity of 35.37%.
CONCLUSION: Tumor M2-PK has a higher sensitivity than markers CEA and CA72-4, and is a valuable tumor marker for the detection of gastrointestinal cancer.