Noninvasive Colorectal Cancer Screening of Benefit to Remote Native Alaskans

Noninvasive Colorectal Cancer Screening of Benefit to Remote Native Alaskans

Findings from a recent study published in the journal Mayo Clinic Proceedings revealed that the cologuard stool DNA testing for colorectal cancer (CRC) is a highly accurate non-invasive screening option for Alaska Native (AN) people, a population with one of world’s highest rates of colorectal cancer.

Colorectal cancer screening rates among Alaska Native (AN) people fall well below the National Colorectal Cancer Roundtable’s target of 80% by 2018. Conventional invasive screening approaches, including colon radiography, sigmoidoscopy, and colonoscopy, present logistic and access challenges for this remote population.

Stool DNA testing, which was approved by the U.S. Food and Drug Administration (FDA) in 2014, may represent a non-invasive screening alternative. The test identifies characteristic chemical changes in stool that signal the presence of cancer or precancerous polyps, and requires no bowel preparation or diet and medication restrictions. Importantly, it can be done from home via a mailed sampling kit. “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 news release.

In the study, entitled Stool DNA Testing for Screening Detection of Colorectal Neoplasia in Alaska Native People,” researchers from the Mayo Clinic and the Alaska Native Tribal Health Consortium performed a prospective study of asymptomatic Alaska Native adults, ages 40-85 years and older, undergoing screening or surveillance colonoscopy between 2012 and 2014. The aim was to evaluate the accuracy of a multi target stool DNA test (MT-sDNA) in comparison with fecal immunochemical testing for hemoglobin (FIT, the reference standard) to detect screening-relevant colorectal neoplasia (SRN). A total of 661 Alaska Native participants took part in the study and submitted stool samples before they underwent screening colonoscopy, which acted as the reference standard.

The results revealed that overall SRN detection by MT-sDNA (49%) was superior to that of FIT (28%). For colorectal cancers, MT-sDNA was 100% accurate versus 80% by FIT. Stool DNA test sensitivity for precancerous polyps improved in proportion to polyp size and with the associated risk of cancer progression. Moreover, its detection sensitivity was of 80% for the largest polyp group (3 cm or larger), and for the important subset of patients with sessile serrated polyps larger than 1 cm (n=9), MT-sDNA detection sensitivity was of 67% versus 11% by FIT.

“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,” said Dr. Ahlquist.

“We were pleased to see the impressive results from this important collaboration,” added Robert Diasio, MD, director of the Mayo Clinic Comprehensive Cancer Center. “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.”

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