Expression of tumor pyruvate kinase M2 isoform in plasma and stool of patients with colorectal cancer or adenomatous polyps

Abstract

Background: Tumor pyruvate kinase M2 isoform (tM2-PK), which is an isoform of PK-glycolytic enzyme and appears on the surface of cancerous proliferating cells, has been used as a diagnostic biomarker for colorectal cancer (CRC). The aim of this study was to evaluate the tM2-PK measurement test for the diagnosis of CRCs and adenomatous polyps in plasma and stool samples in an Iranian population. Methods: In this prospective study, a total of 226 stool and 178 plasma samples were received from patients referred to colonoscopy units. tM2-PK enzyme was measured using two separate ScheBo-Biotech-AG ELISA kits for stool and plasma samples. Results: At the cut-off value of 4 U/ml, in tumor group, the sensitivity of fecal tM2-PK test was 100% and the specificity was 68%, and in polyp group, the sensitivity and specificity were 87% and 68%, respectively. At the cut-off value of 15 U/ml in tumor group, the sensitivity of plasma tM2-PK test was 98% and specificity was 74% and in polyp group the sensitivity and specificity were 98% and 74%, respectively. Based on our results, a cut-off range of 4.8-8 U/ml and >8 U/ml could be used to detect polyp and tumor in stool samples, respectively. Similarly, a cut-off range of 19-25 U/ml and >25 U/ml is recommended in plasma samples for polyp and tumor detection, respectively. Conclusions: This study revealed a high specificity and sensitivity of tM2-PK test for stool and plasma samples in patients with CRC and polyps suggesting it as a non-invasive assay to diagnose CRC and adenomatous polyps.