4 gastroenterologists share their thoughts on Exact Sciences' Cologuard

Although Exact Sciences' Cologuard completed its 2 millionth test, the multitarget stool DNA test remains a topic of contention in the gastroenterology space.

Touting 92 percent sensitivity and 87 percent specificity rates for detecting all stages of colorectal cancer, the test remains a popular alternative for a patient who won't undergo a colonoscopy. Despite the rising prominence of alternatives, colonoscopy is still viewed as the gold standard for CRC detection, according to these specialists, and is a first-line recommend treatment.

Here, four gastroenterologists share their thoughts on Cologuard.

Note: Responses were edited for clarity and style.

Michael Bass, MD, gastroenterologist, Newark, N.J.-based GI Specialists of Delaware

I feel most gastroenterologists would agree Cologuard is a potent weapon in the armamentarium against colon cancer. The 92 percent sensitivity for CRC, and 69 percent sensitivity for detection adenomas with high grade dysplasia, make it the standard second line option, next to colonoscopy.

National screening rates are already well under target, and we will likely see the overall rate decline further, as the push to screen younger people continues to gain traction. Cologuard will likely play an increased role, as we fight to get the younger population screened.

However, a major issue with Cologuard is the false positive rate. The purported rate is 6 percent in those aged 50 to 65. However, DNA methylation occurs during the normal aging process, and thus causes more false positives in people above the age of 65 (a 13 percent false positive rate). One must keep in mind still that many patients above 65 gravitate towards noninvasive testing, because of increased complication rates from colonoscopy and anesthesia.

Alan Gingold, DO, gastroenterologist HIllsborough, N.J.-based Digestive Healthcare Center

Cologuard is a noninvasive stool test that screens for colon cancer. The test was approved in 2016 by the U.S. Preventive Services Task Force as an accepted colon cancer screening option and CMS includes coverage for this test for patients between the ages of 50 and 84 who are considered average risk patients.

The test is actually a combination test which looks for both the genetic material found in colon cancer and some more advanced colon polyps and it detects hemoglobin in the stool using fecal immunochemical testing. The test is about 92 percent sensitive for detecting colon cancer and about 69 percent sensitive for detecting advanced colon polyps. It does have about a 13 percent false positive rate. If a patient has a positive Cologuard test, it is recommended that they then undergo a colonoscopy to evaluate further.

Cologuard is an acceptable option for patients who either are at higher risk for colonoscopy complications, possibly due to underlying breathing or cardiac issues or for patients who for whatever reason would prefer to undergo a less invasive screening option. About 60 percent to 70 percent of people who should be screened for colon cancer are getting screened, yet there is still a significant gap in people who are not getting screened.

Cologuard every three years is one available option for people in need of screening. Other options are colonoscopy every 10 years — or more frequently if polyps are found or patients have other risk factors — yearly FIT testing or fecal occult blood testing. Finally, virtual colonoscopy every five years or flexible sigmoidoscopy every five years, would also be acceptable screening options. Colonoscopy still remains the gold standard and the preferred colon cancer screening test available.

Otto S. Lin, MD, Gastroenterologist, Virginia Mason Medical Center, Seattle

Multitarget fecal DNA testing, sold in the U.S. under the brand name of Cologuard, is currently FDA- approved for CRC screening in average-risk individuals, i.e., those without a family history of colon cancer or a personal history of precancerous polyps.

Cologuard is a stool test that detects genetic mutations commonly seen in colon cancer; it also detects microscopic amounts of blood in the stool. When performed at intervals of every three years, it is covered by Medicare as well as some private insurance plans.

A large study involving 9,989 subjects demonstrated that Cologuard detects 92 percent of CRC, with accuracy almost as good as that of the gold standard test, colonoscopy. However, the accuracy of Cologuard for detecting large precancerous polyps (42 percent) was significantly lower than that of colonoscopy.

Colonoscopy is still considered the preferred screening test for CRC because of its high accuracy and its ability to remove polyps or perform biopsies at the time of the procedure.
However, Cologuard is a viable second-line test for those patients who are unwilling to start off with a screening colonoscopy, as long as they understand that they will need to undergo colonoscopy if the Cologuard test comes back positive.

Paul Limburg, MD, Gastroenterologist, Mayo Clinic, Rochester, Minn., Exact Sciences, Co-chief Medical Officer

CRC is the second leading cause of cancer-related death, yet 1 in 3 Americans age 50 and older are not up-to-date with recommended screening. All the major colorectal cancer guidelines emphasize that choice plays an important role in getting people screened.

Cologuard is a non-invasive colorectal screening test approved for use by men and women, 50 years of age and older, who are at average risk for colon cancer. It is the only non-invasive screening option that has a nationwide, multilingual, patient navigation program. Further, the data show the test is superior to FIT at detecting colorectal cancer (including early-stage cancers and right-sided cancers) and advanced precancerous lesions (including high-grade dysplasia and sessile serrated polyps greater than 1 cm in size).

Since being introduced in 2014, more than 150,000 providers have prescribed Cologuard and over two million people have been screened with Cologuard — nearly half of whom were previously unscreened. The healthcare community agrees that increasing nationwide screening rates is a top priority and we believe Cologuard is an attractive, noninvasive option.

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