Serum and Stool miR-135b Levels as a Potential Diagnostic Biomarker for Colorectal Cancer

Background: By considering the high incidence and mortality rate of colorectal cancer (CRC), finding the noninvasive biomarker for detection of patients with cancer is the main purpose of more and more cancer studies. Methods: In this research, the expression level of miR-135b in serum and stool of patients with colorectal cancer was investigated as a diagnostic marker. Using the real-time PCR, the relative expression level of miR-135b in serum and stool in 40 patients with colorectal cancer, paired with 40 healthy controls, was determined. Then its sensitivity and specificity were rated, via ROC curves analysis. Results: Expression levels of miR-135b in serum and stool of CRC patients were 32.4 and 15.7 times higher in serum and stool, compared to that of healthy control respectively (P<0.05). ROC curves analysis exhibited that serum miR-135b levels were powerful in detecting CRC patients from control subjects, with a sensitivity of 92.7% and a specificity of 89.7% (AUC: 0.929). In addition, stool miR-135b levels strongly distinguished CRC patients from control subjects with a sensitivity of 92.7% and a specificity of 87.2% (AUC: 0.919). Conclusions: The results of the current study indicate that serum and stool miR-135b expression levels seem to be used as a potential diagnostic biomarker for CRC patients. However further studies with large sample size are needed for approving the miR-135b as a noninvasive diagnostic biomarker of CRC.