One Positive FIT and One Negative? Still Do Colonoscopy
Most fecal immunochemical testing as a screen for colon cancer is done with one sample. However, patients with a positive test sometimes request a second test, with the hope it will be negative.
In a Dutch study, there were 21,078 subjects who completed two different fecal immunochemical tests (FITs), both with a positivity cutoff of 15 µg hemoglobin per gram feces. Both FITs were negative in 90% of participants, both positive in 5.5% of participants, and there were discordant results (one positive and one negative FIT) in 4.2% of participants. Patients with 2 positive FITs had higher mean fecal hemoglobin levels and substantial rates of advanced neoplasia (43%) and cancer (7.2%). In patients with discordant results, the rate of advanced neoplasia was still substantial at 21%, and 1.2% had cancer.
Comment:
This study shows that patients with a positive FIT should be sent to colonoscopy, and if the test is repeated and found to be negative, there is still a substantial yield of advanced neoplasia and cancer. Positive FITs should not be repeated in the hope of avoiding colonoscopy.
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):
Wieten E, de Klerk CM, Lansdorp-Vogelaar I, Bossuyt PM, Dekker E, Spaander MCW. A quarter of participants with advanced neoplasia have discordant results from 2-sample fecal immunochemical tests for colorectal cancer screening. Clin Gastroenterol Hepatol 2019 Sep 26. (Epub ahead of print) (https://doi.org/10.1016/j.cgh.2019.09.024)
