[Usefulness of plasma tumor M2-pyruvate kinase in the diagnosis of gastrointestinal cancer].
OBJECTIVE
Pyruvate kinase (PK) is a key enzyme of glycolysis. Different isoforms of this enzyme are tissue-specifically expressed (M2-PK, M1-PK, R-PK, L-PK). The concentration of the dimeric M2-PK is increased in a metabolic state of tumor cells. In this case, the dimeric M2-PK is termed Tumor M2-PK. We investigated EDTA-plasma of 73 patients with gastrointestinal (GI) cancer and 61 healthy controls to evaluate its significance in diagnosing GI cancer.


METHODS
Plasma Tumor M2-PK was measured using an ELISA assay based on two monoclonal antibodies which specifically react with the dimeric Tumor M2-PK.


RESULTS
The sensitivity of Tumor M2-PK was 67.1% for all GI cancers, that of CA 19-9 was 38.4% and that of CEA was 34.3%. The specificity of Tumor M2-PK was 91.8% (cutoff=20 U/mL). Tumor M2-PK showed a high sensitivity in gastric cancer (62.2%), colorectal cancer (66.7%) and bile duct cancer (75.0%). In colorectal cancer, the combination of Tumor M2-PK with CEA resulted in a remarkable increase in the sensitivity (86.2%). The average Tumor M2-PK levels were generally elevated in the metastatic GI cancer patients compared to nonmetastatic patients, especially in stomach cancer with statistical significance (p=0.005).


CONCLUSIONS
Tumor M2-PK in EDTA-plasma seems to be a new valuable tumor marker in GI cancer.
Kim
Chang-Whan
CW
Department of Internal Medicine, College of Medicine, The Catholic University of Korea, St. Mary's Hospital, 62 Yeouido-dong, Yeongdeungpo-gu, Seoul 150-713, Korea.
Kim
Jin Il
JI
Park
Soo-Heon
SH
Han
Joon-Yeol
JY
Kim
Jae Kwang
JK
Chung
Kyu Won
KW
Sun
Hee Sik
HS
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D004067:Digestive System Neoplasms / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011770:Pyruvate Kinase / Q000097:blood*; D012680:Sensitivity and Specificity
D014408:Biomarkers, Tumor; D011770:Pyruvate Kinase