Cologuard: Stool DNA Test Performs Well in Community-Based Setting Among Medicare Beneficiaries

Charles Bankhead

July 2016, Vol 7, No 6 - Colorectal Cancer

The multitarget stool DNA test, a noninvasive screening tool for colorectal cancer (CRC), demonstrated potential for identifying cancer and advanced adenomas in community-based individuals who had previously not followed national screening recommendations, reported Mark Prince, MD, MBA, Director of Gastroenterology, USMD Health System, Arlington, TX, at the 2016 American Association for Cancer Research annual meeting.

Nearly 90% of patients completed the Cologuard stool DNA test when offered the option, and 15% had positive test results that led to a referral for diagnostic colonoscopy. Although none of the 393 patients in the study had undergone screening colonoscopy within the previous 10 years, 90% of those with a positive stool DNA test result followed through with the colonoscopy referral.

“The availability of the multitargeted stool DNA test provided significant medical benefit to our previously screening noncompliant Medicare population,” said Dr Prince. “Patients with clinically critical advanced colorectal neoplasia were identified in this cohort due to high compliance with both stool DNA screening and follow-up diagnostic colonoscopy.”

Although derived from a retrospective chart review, the results provided real-world support for the pivotal multicenter clinical trial that led to the FDA approval of the multitarget stool DNA test as a screening tool for CRC. The pivotal clinical trial involving 10,000 patients showed that the multitarget stool DNA test had a 92% sensitivity for detecting CRC, a 42% sensitivity for detecting colonic adenomas, and an 87% specificity (Imperiale TF, et al. N Engl J Med. 2014;370:1287-1297). The number-needed-to-treat values were 154 with colonoscopy, 166 with the multitarget stool DNA test, and 208 with the fecal immunochemical test.

Good Adherence Rate in the Community Setting

To investigate whether the results of this pivotal clinical trial could be extrapolated to the community, Dr Prince and colleagues reviewed medical records of patients in the USMD Health System, and identified 393 Medicare beneficiaries who had not undergone screening colonoscopy in the previous 10 years, or who had completed a fecal occult blood test more than 1 year ago. All participants had an average risk for CRC.

Overall, 77 providers offered the multitargeted stool DNA test to the 393 screening-noncompliant individuals, and 347 completed the test, representing an 88.3% adherence rate. The test yielded positive results in 51 participants; all patients with positive test results were referred for colonoscopy, and 46 patients followed this recommendation. Of the remaining 5 patients, 3 refused colonoscopy, and 2 were lost to follow-up.

Overall, 4 patients had CRC, 21 patients had advanced adenomatous polyps, 9 patients had nonadvanced adenomas, and 12 patients had neither polyps nor cancer. None of the patients had symptoms before testing positive on the multitargeted stool DNA test.

These results indicate good adherence to the test in the community setting and provide additional evidence that “colon cancer screening saves lives,” said Dr Prince.

“Colonoscopy is the best form of colon cancer screening, but for patients who will not have a colonoscopy, a noninvasive screening test like Colo­guard is needed,” he said.

Dr Prince cautioned that every patient with a positive stool DNA test result should be referred for colonoscopy, which remains the definitive method for detecting CRC and advanced adenomas of the colon.

He added that the applicability of these results to patients with private insurances remains unclear.