Published online Apr 28, 2017. doi: 10.3748/wjg.v23.i16.2891
Peer-review started: December 28, 2016
First decision: January 19, 2017
Revised: February 14, 2017
Accepted: March 30, 2017
Article in press: March 30, 2017
Published online: April 28, 2017
Processing time: 125 Days and 22.5 Hours
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.
ddPCR and quantitative PCR were compared side by side for their performance in the detection of ITGA6 and ITGA6A 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. ITGA6 and ITGA6A 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.
We found that the ddPCR and qPCR methods performed equally well in this TaqMan duplex assay for the detection of ITGA6 and ITGA6A transcripts in stools of patients with colorectal lesions. For ITGA6, receiver operating characteristic (ROC) curve analysis showed comparable areas under the curve of 0.91 (P < 0.0001) and 0.89-0.90 (P < 0.0001) for the prediction of advanced adenomas and colorectal cancers, respectively. ITGA6A, 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 (P < 0.0002). Comparison of the two sets of data revealed a strong correlation of the copy numbers obtained by ddPCR and qPCR for both ITGA6 and ITGA6A.
We found that ITGA6 and ITGA6A detection in stools of patients with colorectal cancers with ddPCR is comparable to that of qPCR using TaqMan assays.
Core tip: We investigated 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 using ITGA6 and ITGA6A as established medium and low abundance stool biomarkers. Our side by side comparison of ddPCR and qPCR on stool samples obtained from patients with advanced adenomas and colorectal cancers and controls using duplex TaqMan reactions revealed that both methods performed equally well.