The science behind the test: stool DNA technology
Cutting-edge stool DNA (sDNA) technology for cancer and precancer detection means more curable-stage cancers can be found than with fecal blood alone.
Cologuard utilizes a multi-target approach to detect DNA and hemoglobin biomarkers associated with colorectal cancer and precancer.
Eleven biomarkers are targeted and provide a stronger connection between colorectal cancer and precancer.
Methylation, mutation, and hemoglobin results are combined in the laboratory analysis to provide a single positive or negative reportable result.
The patient stool samples are processed at the laboratory to isolate the DNA for testing and for detection of fecal occult hemoglobin.
DNA Biomarker Detection
Amplification and detection of methylated target DNA (NDRG4, BMP3), KRAS point mutations, and ACTB (a reference gene for quantitative estimation of the total amount of human DNA in each sample) is performed using the Quantitative Allele-specific Real-time Target and Signal Amplification (QuARTS™) technology.
Multiplexed QuARTS reactions are processed using a real-time cycler with each biomarker (NDRG4, BMP3, KRAS, and ACTB) monitored separately through independent fluorescent detection channels.
Hemoglobin Biomarker Detection
The stool sample is prepared and analyzed for fecal occult blood in a quantitative Enzyme-Linked Immunosorbent Assay (ELISA) that determines the concentration of hemoglobin in the sample.
Control samples for both the QuARTS assays and hemoglobin assay are tested along with patient samples to show that the process has been performed appropriately.
Outputs from the DNA and hemoglobin are integrated during analysis with an algorithm to determine a Cologuard positive or negative result.