The use of noninvasive colorectal cancer screening via a multi-target stool DNA test (mt-sDNA) detected the disease in patients who had previously avoided more invasive screening procedures, according to the results of a study presented at the 2016 American Association for Cancer Research (AACR) Annual Meeting, held April 16–20 in New Orleans (abstract LB-296).
“Despite the availability of various colon cancer screening options, more than 40% of Americans are not getting screened,” said Mark Prince, MD, MBA, director of gastroenterology with USMD Physician Services, a health system based in Dallas, Texas, in a press release. “This study highlights the opportunity to expand the screening population by offering new, patient-friendly methods.”
The mt-sDNA test, called Cologuard, was approved by the US Food and Drug Administration in August 2015. The test detects red blood cells and DNA mutations that can be associated with colon cancer.
In this study, Prince and colleagues reviewed the medical records of Medicare patients at average risk for colorectal cancer who were non–screening compliant. They then offered the mt-sDNA test to patients who were more than 10 years from their last colonoscopy and/or more than 1 year from their last fecal occult blood test. Patients with a positive mt-sDNA test were advised to undergo colonoscopy.
“We were interested to see whether the ‘real-life’ experience with Cologuard in clinical practice would be similar to the results seen in the clinical trial,” Prince said.
Over the course of a year, 77 providers order 393 mt-sDNA tests and 88.3% of patients were completed. The tests were negative for 85.3% of patients and positive in 14.7%. Forty-six of the 51 patients with positive tests underwent colonoscopy. Colonoscopy revealed colon cancer in 4 patients, advanced adenomas in 21 patients, non-advanced adenoma in 9 patients, and negative results in 12 patients (23%).
The positive predictive value for the test for advanced colorectal lesions was 54.3% and for any colorectal neoplasia was 73.9%.
In the press release, Prince said a limitation of the study is that it involved only patients who were eligible for Medicare. “It will be interesting to analyze the use in commercially insured patients when insurance coverage becomes more widespread,” he said. Prince also cautioned that any positive results from noninvasive screening tests should be followed up by a colonoscopy.