For many years, doctors have been confused about why colon cancer can develop in people who find nothing on colonoscopy. A new discovery from Oklahoma Medical Research may help explain why, and this discovery may detect these cancers earlier and more effectively.
Just behind lung cancer, colon cancer is another leading cause of cancer death in men and women, killing 65,000 Americans every year. If cancer is detected early, the life expectancy will still be greatly improved: the five-year survival rate of people who detect colon cancer early is 90%, and the survival rate of patients who are found late is 8%. The most common screening method is colonoscopy, however, during these tests, certain cancer-causing polyps are easily missed.
Dr. David Jones said that some polyps are embedded in the surface of the colon and are usually flat and covered. This makes them difficult for doctors to discover. It is believed that patients with colonoscopy who have no polyps develop colon cancer through an unknown mechanism that does not involve polyps. It is now clear that up to 30% -40% of these hidden polyps may develop into colon cancer.
Most cancers and most polyps have more than one mutation, but in these polyps, only one gene called BRAF is mutated. Because these indicator markers can identify polyps, it is possible to create a diagnostic test to analyze a stool sample to find these changes before a colonoscopy. If there are changes, this will be the way doctors know to find hidden polyps. Understanding the downstream effects of BRAF mutations may allow drug intervention to prevent this cascade of DNA changes from occurring completely. Ultimately, this may prevent the development of colon cancer.