AACR 2016: Cologuard Detected Colorectal Cancer in Previously Unscreened Patients
A noninvasive colorectal cancer-screening test detected the disease in patients who had previously avoided more invasive screening measures, according to research presented by Prince et al at the 2016 AACR Annual Meeting (Abstract LB-296). The study of nearly 400 patients revealed four patients with cancers and 21 with advanced adenoma, or polyps.
“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 at USMD Physician Services. “This study highlights the opportunity to expand the screening population by offering new, patient-friendly methods.”
Cologuard Background
In August 2014, the U.S. Food and Drug Administration approved Cologuard, a multitarget stool DNA test (mt-sDNA) that detects the presence of red blood cells and DNA mutations that can be associated with colon cancer. In October 2014, Cologuard was approved for Medicare coverage.
A 10,000-patient, prospectively conducted clinical trial for Cologuard, published by Imperiale et al in The New England Journal of Medicine, showed that Cologuard is 92% sensitive for detecting colorectal cancer and 42% sensitive for precancer, with a specificity of 87%.
Study Findings
In the current study, Dr. Prince and colleagues performed a retrospective medical records review of Medicare-eligible patients treated by physicians in the USMD Physician Services. The study focused on patients at average risk for colorectal cancer—those without symptoms, those with a personal or family history of colorectal cancer, and those with polyps—who were not previously compliant with recommended guidelines for screening.
“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,” Dr. Prince said.
The patients’ clinicians offered Cologuard screening to patients who had not had a colonoscopy screening in 10 or more years, or a fecal occult blood test in a year or more. During the 12-month study period, from October 2014 to September 2015, USMD providers ordered 393 mt-sDNA studies, and 347 patients completed the test, achieving 88.3% compliance. Fifty-one patients, representing 14.7% of the total, tested positive by Cologuard and were referred for diagnostic colonoscopies.
According to Dr. Prince, 46 patients, or 90.2 % of those referred, received the follow-up colonoscopies. Three patients refused the procedure and two patients did not respond to physicians’ attempts to follow up.
Among the 46 patients who had follow-up colonoscopies, 4 were diagnosed with colon cancer. A total of 21 were diagnosed with advanced adenoma or polyps, 9 had nonadvanced adenoma, and 12 tested negative.
Dr. Prince said the discovery of four cases of colon cancer and numerous polyps, which have the potential to develop into cancer, supported the findings of the clinical trial. He noted that none of the patients had reported any symptoms and all had previously refused colonoscopies.
“Colon cancer screening saves lives,” Dr. Prince said. “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.”
Dr. 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. He also cautioned that any positive results from noninvasive screening tests should be followed up by a colonoscopy.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
