Detection of Colorectal Cancer in Peripheral Blood by Septin 9 DNA Methylation Assay

From public health as well as health economics perspectives, the poor adoption of current screening options limits the effectiveness of CRC screening initiatives; as stated by Sidney Winawer, MD, "the best test is the one that gets done." Current CRC screening guidelines include FOBT, sigmoidoscopy (alone or with FOBT), or colonoscopy. Non-invasive screening is conducted using FOBT, which while inexpensive, exhibits a low compliance rate (around 16% in the US) due to its use restrictions, perceived inconvenience and lack of consumer acceptance. The gold standard procedure for CRC detection is colonoscopy; it exhibits excellent performance characteristics, but has a limited utility as a first line screen due to its high cost, healthcare delivery resource limitations, and inadequate patient acceptance. It is believed a noninvasive, first-line screening assay capable of detecting individuals with colorectal disease, confirmed by colonoscopy, would have greater utility for population screening.

Epigenomics has identified methylated gene regions that are specific for colorectal cancer or pre-malignant tissue. Aberrantly methylated genes represent attractive candidate markers for cancer screening, as cancer-specific methylation changes occur early in tumorigenesis, appear to be stable, yield a positive amplifiable signal, and can be assayed with high analytical sensitivity. Since methylation occurs early and in distinct genomic areas, it is possible to achieve high clinical sensitivity with a small number of methylated DNA markers. Studies have shown that aberrantly methylated DNA markers can be detected in tissue and body fluids and are highly correlated to colorectal cancer.