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Stool DNA test provides accurate CRC screening for Alaska Natives
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Cologuard’s multitarget stool DNA test was found to provide accurate colorectal neoplasia screening for Alaska Native people, who have one of the world’s highest rates of colorectal cancer and limited access to traditional screening methods.
“Stool DNA detects colorectal cancer and highest risk precancerous polyps with high accuracy, and its application within a screening program could translate into more effective prevention and control of the leading cancer among Alaska Native people,” David Ahlquist, MD, study author and co-inventor of the stool DNA test, said in a press release.
Ahlquist and colleagues performed a prospective, cross-sectional study to compare the accuracy of the multitarget stool DNA test (Cologuard, Exact Sciences) and the fecal immunochemical test (FIT; OC-Sensor Diana, Polymedco) for detecting screening-relevant colorectal neoplasia. They enrolled 868 asymptomatic Alaska Native people aged 40 to 85 years who provided stool samples before a screening or surveillance colonoscopy (used as the reference standard) between February 2012 and August 2014 at the Alaska Native Medical Center in Anchorage.
“The high detection rates of cancer and large polyps by stool DNA that we found in the Alaska Native population are remarkably similar to those demonstrated in the multicenter 10,000 patient screening study of the general U.S. population reported in the New England Journal of Medicine in 2014,” Ahlquist said.
Overall, 661 patients (60% women; median age, 55 years) completed the study. Screening-relevant neoplasia detection rates were 49% (95% CI, 38%-60%) for the stool DNA test compared with 28% (95% CI, 19%-39%) for FIT (P < .001), and in the screening group the respective rates were 50% (95% CI, 37%-63%) vs. 31% (95% CI, 20%-44%; P = .01).
The stool DNA test was superior to FIT for detecting advanced adenoma at all sizes. For adenomas 2 cm or larger at high risk of progression, the stool DNA test’s sensitivity was 62% compared with 29% by FIT (P = .05). The stool DNA test’s sensitivity increased with adenoma size — up to 80% for those 3 cm or larger (P = .01 trend).
The stool DNA test also detected 67% of sessile serrated polyps larger than 1 cm compared with 11% by FIT (P = .07), and detected 100% of CRCs compared with 80% by FIT (P = .48). Overall specificities were 93% (95% CI, 90%-95%) for the stool DNA test compared with 96% (95% CI, 93%-98%) for FIT (P = .03).
The researchers concluded that based on these findings, a screening program using the stool DNA test has the potential to accurately detect screening-related neoplasia and reduce CRC incidence and mortality in the Alaska Native population.
“We were pleased to see the impressive results from this important collaboration,” Robert Diasio, MD, director of the Mayo Clinic Comprehensive Cancer Center, said in the press release. “Colorectal cancer mortality should be entirely preventable with use of effective screening tools. Yet, many Americans remain unscreened because of their reticence to undergo invasive procedures as well as to barriers of inconvenience or limited access. The stool DNA test represents an accurate, patient-friendly and readily accessible new option that we hope will lead to improved screening participation rates in Alaska and across the country.” – by Adam Leitenberger
Disclosures: Ahlquist and Mayo Clinic report they have a financial interest in Cologuard. Please see the study for a full list of all other researchers’ relevant financial disclosures.
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