Droplet Digital PCR for Quantification of in a Stool MRNA Assay for the Detection of Colorectal Cancers

Aim: To investigate the use of droplet digital polymerase chain reaction (ddPCR) for detecting host mRNA markers in stools as a non-invasive test for colorectal cancer screening.

Methods: ddPCR and quantitative PCR were compared side by side for their performance in the detection of and transcripts in stool samples obtained from patients with various types of colorectal lesions (advanced adenomas and stage II-IV colorectal cancers) and control (patients displaying no pathological findings) using duplex TaqMan reactions for both methods. and were chosen for this proof-of-concept study based on their relative medium and low abundance in stool samples, respectively, as established in a previous study.

Results: We found that the ddPCR and qPCR methods performed equally well in this TaqMan duplex assay for the detection of and transcripts in stools of patients with colorectal lesions. For , receiver operating characteristic (ROC) curve analysis showed comparable areas under the curve of 0.91 ( < 0.0001) and 0.89-0.90 ( < 0.0001) for the prediction of advanced adenomas and colorectal cancers, respectively. , which was detected at very low levels in control patients, was found to be significantly elevated (over 40 times) in stage II and III colorectal cancers ( < 0.0002). Comparison of the two sets of data revealed a strong correlation of the copy numbers obtained by ddPCR and qPCR for both and .

Conclusion: We found that and detection in stools of patients with colorectal cancers with ddPCR is comparable to that of qPCR using TaqMan assays.