Protein Assays Added to the Fecal Immunochemical Test Improve Sensitivity for Advanced Adenomas
Douglas K. Rex, MD, MASGE, reviewing de Klaver W, et al. Ann Intern Med 2021 Jul 20.
The fecal immunochemical test (FIT) is widely chosen by organized colorectal cancer (CRC) screening programs as the screening test of choice. FIT detects about 80% of CRC, is inexpensive, and has a specificity of 96%. The main competitor to FIT in the U.S. has been the multitarget DNA stool test combined with FIT, which often is considered too costly for use outside the U.S.
The current study from the Netherlands tested whether the addition of various protein assays could improve the sensitivity of FIT. The researchers used stool samples from screening studies performed about 10 years ago. Analysis of 9 different fecal proteins showed that a combination of hemoglobin, calprotectin, and serpin family F member 2 resulted in the best performance. This combination was called mtFIT.
Compared to FIT, the mtFIT improved sensitivity from 37.3% to 42.9% for advanced neoplasia. There was no improvement in sensitivity for CRC or advanced serrated lesions, and the improvement in overall sensitivity for advanced neoplasia was entirely from detecting more advanced adenomas, for which sensitivity increased from 28.1% to 37.8%. These improvements in sensitivity for advanced adenoma were maintained when the specificities of FIT and mtFIT were set at the same level.
A cost analysis suggested that the mtFIT could cost as much as twice that of FIT and still be cost-effective.
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.
de Klaver W, Wisse PHA, van Wifferen F, et al. Clinical validation of a multitarget fecal immunochemical test for colorectal cancer screening: a diagnostic test accuracy study. Ann Intern Med 2021 Jul 20. (Epub ahead of print) (https://doi.org/10.7326/m20-8270)