There is uncertainty as to the appropriate follow-up of patients who test positive on multimarker stool DNA (sDNA) testing and have a colonoscopy without neoplasia.
Dr Gregory Cooper and colleagues determined the prevalence of missed colonic or occult upper gastrointestinal neoplasia in patients with an apparent false positive sDNA.
The researchers prospectively identified 30 patients who tested positive with a commercially available sDNA followed by colonoscopy without neoplastic lesions.
Patients were invited to undergo repeat sDNA at 11–29 months after the initial test followed by repeat colonoscopy and upper endoscopy.
|The positive predictive value was 0.60 |
|Digestive Diseases & Sciences|
The researchers determined the presence of neoplastic lesions on repeat evaluation stratified by results of repeat sDNA.
The team restudied 12 patients.
The team found that 7 patients had a negative second sDNA test and a normal second colonoscopy and upper endoscopy.
In contrast, 5 of 12 subjects had a persistently positive second sDNA test, and 3 had positive findings, including a 3-cm sessile transverse colon adenoma with high-grade dysplasia, a 2-cm right colon sessile serrated adenoma with dysplasia, and a nonadvanced colon adenoma.
These corresponded to a positive predictive value of 0.60 and a negative predictive value of 1.00 for the second sDNA test.
In addition, the medical records of all 30 subjects with apparent false positive testing were reviewed and no documented cases of malignant tumors were recorded.
Dr Cooper's team comments, "Repeat positive sDNA testing may identify a subset of patients with missed or occult colorectal neoplasia after negative colonoscopy for an initially positive sDNA."
"High-quality colonoscopy with careful attention to the right colon in patients with positive sDNA is critically important and may avoid false negative colonoscopy."