Colorectal cancer (CRC) is one of the major healthcare problems worldwide. Both the incidence and death rates from CRC are increasing rapidly in Asian countries. CRC screening allows the detection and removal of early stage lesions, and has been demonstrated to reduce both CRC morbidity and mortality. Currently the clinical gold standard used in CRC to monitor disease development is serum CEA, yet the biomarker is frequented with low specificity and sensitivity. Recent epigenetic studies suggested that microRNAs (miRNAs) may help to better categorize the CRC subtypes and predict the outcomes. Owing to their small size, reduced degrading potential, remarkable stability in most tissues and liquid biopsies; they have been found to serve as valuable signatures for numerous disease conditions, particularly cancer.
In this study we investigated the potential of serum miRNAs as biomarker for screening CRC patients. We determined the serum miR-139-3p, miR-187 and miR-622 levels in 42 control subjects and 42 CRC patients, and expressed the results as delta Ct normalized by U6 (i.e., the higher the delta Ct, the lower the level).
Serum miRNA-139-3p and miR-187 levels were significantly lower in CRC patients than in control (5.859 vs 0.428 and 7.461 vs 1.318, p < 0.001, respectively). On the other hand, serum miR-622 was detectable in 24 out of 42 (∼57%) CRC patients whereas in only 6 out of 42 (∼14%) control (p < 0.001). We further compared the performance of serum miR-139-3p with CEA as diagnostic biomarker. All control samples showed CEA value lower than 3 ng/ml, whereas 60% of CRC patients showed CEA value ≥ 3 ng/ml. The sensitivity was 60% and specificity was 100% (AUC: 0.845). The positive and negative predictive values were 100% and 62%, respectively. For miR-139-3p (threshold delta Ct = 2.205), the sensitivity was 100% and specificity was 80% (AUC: 0.971). The positive and negative predictive values were 87.7% and 100%, respectively. These results suggested that miR-139-3p was a better diagnostic biomarker for identifying all CRC patients.
To conclude, our results showed that miRNAs serve as new approach of diagnostic biomarker, though a larger sample size and multi-centre performance test are warranted to validate the feasibility.
Clinical trial identification
All authors have declared no conflicts of interest.