March 04, 2020
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Multitarget stool DNA has high positive predictive value in CRC

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Non-invasive screening with multitarget stool DNA tests had a high positive predictive value for any colorectal neoplasia regardless of a patient’s exposure to previous colonoscopy, according to study results.

John B. Kisiel, MD, of the division of gastroenterology and hepatology at Mayo Clinic in Rochester, Minnesota, and colleagues wrote that multitarget stool DNA (MT-sDNA) testing amplifies methylated BMP3 and NDRG4, mutant KRAS and beta-actin and measures hemoglobin through immunochemical testing.

“MT-sDNA utilization has increased substantially since its approval and subsequent inclusion in the U.S. Preventive Services Task Force CRC screening guidelines; promising post-approval data on test performance are now emerging on a limited scale,” they wrote. “We sought to evaluate the PPV of MT-sDNA for all colorectal neoplasia and by lesion subtype based on site, histology, and the presence/absence of advanced features. These features were evaluated both in the overall cohort as well as in groups stratied by patients’ previous exposure to screening colonoscopy.”

Researchers identified consecutive patients who completed a MT-sDNA test and reviewed the records of those with positive tests for neoplastic findings at diagnostic colonoscopy. They calculated the test’s positivity rate, adherence to diagnostic colonoscopy and the positive predictive value of MT-sDNA for any colorectal neoplasia and neoplastic subtypes.

Of 16,469 completed tests, 2,326 patients received positive results (14.1%), and after excluding those with increased risk for CRC, 1,558 of the 1,801 remaining patients (87%) underwent diagnostic colonoscopy. Of these patients, 918 had undergone previous colonoscopy (59%).

Investigators determined that any colorectal neoplasia was found in 1,046 of patients who underwent diagnostic colonoscopy (positive predictive value = 67%). Although more neoplastic lesions were found in patients without previous colonoscopy (73%), rates were still high among those who had (63%, P < .0001).

Kisiel and colleagues also found that 79% of patients had right-sided neoplasia, which they wrote is an area of limitation for other screening methods.

“The high prevalence of right-sided CRN detected by MT-sDNA seen in our study suggests potential advantages over other currently available screening modalities for CRC, which could ultimately prove valuable in reducing CRC morbidity and mortality,” they wrote. – by Alex Young

Disclosure: The Mayo Clinic and Exact Sciences own intellectual property under which Kisiel is listed an inventor and may receive royalties. Please see the full study for all other authors’ relevant financial disclosures.