At Home Colon Cancer Screening Test in the Works
A promising non-invasive at-home colon cancer screening test was presented last week at the American Association for Cancer Research conference. Mayo Clinic researchers developed the test in collaboration with Exact Sciences Inc. which has detected 85% of colon cancers in a clinical study.
Test Detected 87% of Early Stage Colon Cancers
Colon cancer is the second leading cause of cancer death for men and women in the United States with about 100,000 new cases diagnosed each year. Yet, unfortunately, only about 40% of adults adhere to the recommended screening schedule, likely because of the invasive nature of the “gold standard” – the colonoscopy.
Dr. David Ahlquist MD, a professor of medicine and consultant in gastroenterology at the Mayo Clinic, and colleagues say that the test identifies DNA mutations (methylations) in stool samples that are associated with the presence of tumors. “The noninvasive test we have developed is simple for patients, involves no diet or medication restriction, no unpleasant bowel preparation, and no lost work time, as it can be done from home,” says Ahlquist.
The clinical study was based on results from more than 1,100 frozen stool samples from patients with and without colorectal cancer. The test accurately identified 85.3 percent of colorectal cancers and 63.8 percent of colon polyps bigger than 1 centimeter, which are considered pre-cancers and likely to progress to cancer said Ahlquist.
The detection rate was 87% for cancers in stages I through III (considered the most curable) and 69% percent for stage IV, the most advanced. Dr. Ahlquist says that tumors become less methylated in later stages, explaining the better accuracy of the test for early stage cancers.
The test, called the Cologuard sDNA test, is unique in that it was able to identify cancers in all locations throughout the colon. If approved for use, it would be followed by a colonoscopy if positive results are found.
The researchers say that the test needs at least another year of development before it is ready for clinical use. Another clinical trial is expected to start in 2011.
Cost is yet undetermined, but Ahlquist says that it is expected to be more than a fecal occult blood test (about $23) but less than a colonoscopy ($700).
Ahlquist D, et al "Next generation stool DNA testing for detection of colorectal