When Colonoscopy for a Positive Cologuard Is Negative, STOP the Workup

The Cologuard test from Exact Sciences looks for hemoglobin and abnormal DNA in the stool. Because abnormal DNA can be shed from the GI tract proximal to the colon, or coughed up from the lungs or larynx and swallowed, there has always been the question of whether patients with a negative colonoscopy done for a positive Cologuard should undergo additional workup. Early studies suggested additional workup is unnecessary, and now another study indicates the same.

Using patients from the pivotal study that led to Cologuard FDA approval, investigators followed 1216 patients with a negative colonoscopy (normal or only nonadvanced adenomas) for at least 6 months and mean 5.4 years. The group included 205 patients who had a positive Cologuard (mean age 68 years) and 1011 with a negative Cologuard (mean age 67 years). Aerodigestive cancers (including 1 colon cancer) occurred in 5 persons in the positive group versus 11 in the negative group (none were colon cancer; adjusted risk ratio for positive vs negative group, 2.2; p=.15). Compared to Surveillance, Epidemiology, and End Results Program (SEER) data (expected population rates), the negative Cologuard group had a lower rate of aerodigestive cancers (risk ratio, 0.4; p=0.0008). The positive Cologuard group rate was similar to the rate in the SEER data (risk ratio, 0.8; p=.6).

Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

Douglas K. Rex, MD, FASGE

Citation(s):

Berger BM, Kisiel JB, Imperiale TF, et al. Low incidence of aerodigestive cancers in patients with negative results from colonoscopies, regardless of findings from multi-target stool DNA tests. Clin Gastroenterol Hepatol 2019 Aug 5. (Epub ahead of print) (https://doi.org/10.1016/j.cgh.2019.07.057)