A new home-based screening test for colon cancer has recently hit the scenes. Cologuard or stool DNA testing was approved by the U.S. Food and Drug Administration this past August and is covered by Medicare.
The test looks for cancer-related DNA and red blood cells in a person’s stool. On the one hand, it doesn’t require the unpleasant preparation that is needed for a colonoscopy. But on the other hand, the $600 cost, which is not yet covered by private insurers, is much greater than the $25 it costs for a more basic fecal occult blood test, also called a FIT test.
“It’s a good test. It’s better than the stool occult blood test. Cologuard detected 92 percent of colorectal cancers and 42 percent of advanced adenomas, or polyps, in the study population, while the FIT screening test detected 74 percent of cancer and 24 percent of advanced adenomas. But it’s a very new test,” said Fadi Deeb, M.D., a local gastroenterologists, who also serves as TMC’s section chief for gastroenterology, “and we don’t know how often we should do it, every two years, every three years, or every five years? Intervals have not been tested, so we just don’t know.”
Given its $600 cost, which is equal to 24 FIT tests, it would be interesting to see a study comparing one Cologuard to 20-24 consecutive FIT tests over a period of one to three years, in detecting colon cancer and advanced adenomas. Dr. Deeb said.
It is not currently recommended as a method to screen for colorectal cancer by the United States Preventive Services Task Force. The USPSTF recommends adults age 50 to 75 who are at average risk for colon cancer to be screened using fecal occult blood every year, a sigmoidoscopy every five years plus stool occult blood every three years, or colonoscopy every 10 years.
Dr. Deeb said the new test had its limitations. “You can’t use it if you have a personal history of colon polyp, colon cancer, a family history of colon cancer, ulcerative colitis, Crohn’s disease, familial adenomatous polyposis or bleeding hemorrhoids.”
Cologuard was not test directly against colonoscopy for screening. “Colonoscopy is the gold standard” and is more effective in detecting precancerous polyps, which can be removed during the same procedure. Regular screening for and removal of these polyps with a colonoscopy can reduce a person’s risk of developing colorectal cancer by up to 90 percent.
This new test has a false-positive rate of about 13 percent, meaning those people will likely need to undergo a colonoscopy to rule out cancer.
“The test is an option for certain patients who don’t like invasive procedures or for those who can afford it,” he said.