Can a Stool DNA Test Diagnose Colorectal Cancer Early?

According to a comprehensive study in the reliable British medical journal “New England Journal of Medicine,” a stool DNA test can identify lesions (abnormal tissue) with cancerous potential in the large bowel, determine colorectal cancer risk and allow timely intervention to prevent cancer development.

Colorectal cancer is among the 5 most common and deadliest cancers. Although possible at any age, it usually occurs after 50. Like other cancers, it often causes no symptoms until advanced, making earlier detection essential. Substantial advances over the last 20 years introduced screening programs and greatly reduced incidence and mortality. Colonoscopy is commonly used, imaging the bowel wall with a camera to identify potentially cancerous lesions and enable early intervention. Fecal immunochemical testing for hidden blood (FIT) is also used. Results are good, but lesions may sometimes be missed, prompting research into alternatives. Fecal DNA testing is currently particularly emphasized. It analyzes DNA shed into stool from tumors or potentially tumorous lesions. Many studies show some benefit, but advantages, disadvantages and usefulness compared with other screening tests remain unclear. One recent study in the British medical journal compared FIT with fecal DNA testing.

The study involved 65 people with cancer and 757 with potentially cancerous lesions among approximately 10.000 participants, all undergoing FIT and fecal DNA testing to assess success. Cancer detection was %92 with fecal DNA and %74 with FIT; detection of advanced potentially cancerous lesions was %42 and %24 respectively. Fecal DNA also detected more potentially cancerous polyps. However, it also produced more false positives, incorrectly identifying healthy people as affected.

In conclusion, fecal DNA appears much more advantageous than FIT for detecting cancer and potentially cancerous lesions. Although its false-positive rate is somewhat higher, this is not a serious disadvantage beside its benefits. Working entirely with stool also avoids discomfort during colonoscopy. Nevertheless, being very new and more expensive than alternatives limits current use. If developed further with advantages and disadvantages established, it would be unsurprising for it to become indispensable in early colorectal cancer diagnosis in the near future.