DNA test provides hope for new cancer screening tool

Research is providing insight into a new screening tool not only for colon cancer but also for gastrointestinal cancers above the colon. According to a report on MedicineNet.com, Dr. David Ahlquist has been researching a stool based DNA test at the Mayo Clinic in Rochester Minnesota. Ahlquist maintains that screening for DNA in the stool rather than looking for blood makes more sense since using blood as a marker has limitations. Currently, the fecal occult blood test (FOBT) which screens for blood in the stool, and the colonoscopy are commonly used to detect colon cancer.  But Ahlquist explained, “most polyps basically don’t bleed. In contrast, all precancerous polyps shed cells that contain abnormal DNA. So, a stool-based DNA test is a strategically more rational approach.”

As part of his research, Ahlquist also screened stool samples for signs of cancer higher up in the digestive system including the esophagus, pancreas, stomach and other organs.  In an interview for Minnesota Public Radio he explained why. “What’s common to all of these cancers is that they shed cells into the GI passageway that are ultimately excreted with stool, so by doing a stool DNA test, one has the potential to detect all of these cancers.”

According to MPR, Ahlquist’s researchers analyzed 140 samples, 70 from people with known GI cancers, and 70 from people without cancer. Of those, 100 percent of the stomach and colon cancers were detected. But only 62 percent of pancreatic cancers were detected. Early-stage cancers were as likely to be found as late stage.

Some caution, however, that while the test offers promise, it still does not offer enough accuracy to be dependable. Dr. Selwyn Vickers, Associate Director of the Masonic Cancer Center at the University of Minnesota was also interviewed by MPR for the report.  He said, “there is still a long way to go before we can say its application is going to bring value. It does bring hope, and those are two different things.”

To read or listen to the full Minnesota Public Radio interview with Dr. Ahlquist about screening for cancers above the colon, click here.
To read “New DNA Stool Testing Spots More Colon Cancers” on MedicineNet, click here.