Colorectal Cancer Screening Test
The Stool-Based DNA Screening Approach
Every day, millions of normal epithelial cells are shed from the colon wall into the stool stream and, as they degenerate, release their DNA.
As polyps develop, they also shed cells into the stool stream. Some of these cells contain altered DNA, reflecting acquired mutations associated with colorectal neoplasia. Although the polyp may cause bleeding, it may only occur from time to time, and may not be recognized as a symptom. However, at the same time, cells from this potentially cancerous polyp are shed continuously, and can provide a detectable amount of altered DNA in the stool specimen.
During this early stage, a stool-based DNA (sDNA) screening test could be prescribed by a healthcare provider. From a whole stool sample, the patient collects approximately 8g of stool, about the size of a large grape, with the provided materials, and forwards the specimen to a laboratory for analysis.
Through a series of sophisticated laboratory procedures, the specimen is homogenized and purified, and specific DNA targets are isolated. Target DNA is then amplified and analyzed for molecular alterations associated with cancerous and pre-cancerous conditions of the colon and rectum. If a DNA abnormality is identified, a colonoscopy must be performed.
Although the science behind stool-based DNA screening is very sophisticated, the specimen collection process is very simple. Sample collection requires:
- No bowel preparation
- No medication or dietary restrictions
- No lost time from a patient's daily routine