A Tissue-Based Comparative Effectiveness Analysis of Biomarkers for Early Detection of Colorectal Tumors

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OBJECTIVES:We recently identified a six-gene methylation-based biomarker panel suitable for early detection of colorectal cancer (CRC). In this study, we compared the performance of this novel epi-panel with that of previously identified DNA methylation markers in the same clinical tissue sample sets.METHODS:Quantitative methylation-specific PCR was used to analyze the promoter region ofSEPT9andVIMin a total of 485 tissue samples, divided into test and validation sets.ITGA4,NTRK2,OSMR, andTUBG2were also included in the analyses. Receiver operating characteristic (ROC) curves were used to compare the performances of the individual biomarkers with that of the novel epi-panel.RESULTS:SEPT9andVIMwere methylated in 82 and 67% of CRCs (n=169) and in 88 and 54% of the adenomas (n=104). Only 3% of the normal mucosa samples (n=107) were methylated for these genes, confirming that the methylation was highly cancer-specific. Areas under the ROC curve (AUC), distinguishing CRCs from normal mucosa, were 0.94 forSEPT9and 0.81 forVIM. AUC values for separating adenomas from normal mucosa samples were 0.96 and 0.81 for the same genes. In comparison, the novel epi-panel achieved an AUC of 0.98 (CRC) and 0.97 (adenomas).ITGA4, OSMR, NTRK2, andTUBG2were methylated in 90, 78, 7, and 1% of the CRCs, and in 76, 77, 3, and 0% of the adenomas. Between 0 and 2% of the normal mucosa samples were methylated for the same genes.ITGA4andOSMRachieved an AUC of 0.96 and 0.92 (CRC vs. normal mucosa), and 0.93 and 0.92 (adenomas vs. normal mucosa).CONCLUSIONS:We have confirmed the high performance of some of the previously identified DNA methylation markers. Furthermore, we showed that a recently reported epi-panel performed better than the individual DNA methylation biomarkers when analyzed in the same tissue samples. This observation was also true forVIMandSEPT9, which are included in commercially available noninvasive tests for CRC. These results further underscore the value of combining a manageable number of individual markers into a panel, which in addition to having a higher sensitivity and specificity might provide a more profound robustness to a noninvasive test compared with single markers.

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