Diagnostic value of pyruvate kinase isoenzyme type M2 in colon cancer proven with colonoscopy

Abstract

Background: Colonoscopy is the gold standard for colon cancer screening; it is also associated with a high cost and complication. Proliferating cells, in particular tumor cells, express a dimeric isoenzyme of pyruvate kinase, termed M2 pyruvate kinase (M2-PK). The aim of this study was to determine the diagnostic accuracy of fecal M2-PK for colon cancer. Materials and Methods: Forty-nine patients with colon cancers and 49 healthy controls were selected consecutively among individuals undergoing screening colonoscopy for various indications. The diagnosis was confirmed by histology. M2-PK measurements were done by enzyme-linked immunosorbent assay of fecal occult blood test (FOBT) and immunological FOBT (IFOBT) according to the manufacturer's instructions. Results: M2-PK > 9 (U/mL) was the best cutoff point in the detection of colon cancers. In this cutoff point, sensitivity and specificity were 87.8 and 91.8, respectively, and accuracy was 89.8. The sensitivity and specificity of IFOBT were 93.9 and 100, respectively, and accuracy was 96.9. The sensitivity and specificity of FOBT were 65.3 and 100, respectively, and accuracy was 82.6. Conclusion: IFOBT with high sensitivity and specificity and accuracy and low cost is the best fecal screening test. The current study suggests that fecal M2-PK can be used for high-risk colon cancer patients and negative IFOBT that refused colonoscopy as a precolonoscopy screening test.