Diagnostic performance of 5 FITs varied for detection of advanced colorectal neoplasia
The differences among the fecal immunochemical tests (FITs) in the cross-sectional study show that choice of FIT clearly matters and that FITs should not be considered interchangeable in screening programs for colorectal cancer, an ACP Journal Club commentary said.
A recent study comparing common fecal immunochemical tests (FITs) found that they varied substantially in their performance. Patients ages 50 to 85 years at three U.S. academic medical centers completed five FITs (Hemoccult ICT, Hemosure iFOB, OC-Light S FIT, QuickVue iFOB, and OC-Auto FIT) before screening or surveillance colonoscopy. Of the 3,761 participants, 320 had advanced colorectal neoplasia, including nine with colorectal cancer. Sensitivities for the FITs ranged from 10.1% to 36.7% and specificities ranged from 85.5% to 96.6% for detection of advanced colorectal neoplasia (ACN).
The study was published Sep. 3 in Annals of Internal Medicine and summarized in the September ACP Gastroenterology Monthly. The following commentary by Dushyant Singh Dahiya, MD, ACP Member, and Prateek Sharma, MD, FACP, was published Dec. 3 in the ACP Journal Club section of Annals of Internal Medicine.
In the USA, 1 in 3 adults are overdue for colorectal cancer (CRC) screening. An emerging challenge is the increasing incidence of CRC in persons <50 years of age. Although endoscopic visualization is considered the gold standard for CRC detection, stool-based tests such as FIT are a convenient and cost-effective option with relatively high adherence rates and may help to direct screening efforts.
The study by Levy and colleagues shows a stark difference in the sensitivity of 5 FITs, ranging from 10.1% to 36.7%. Brand of FIT and location of ACN affected sensitivity (distal lesions had higher detection rates). The specificity was as high as 85.5% to 96.6%. As such, the choice of FIT is a complex decision and one that clearly matters—FITs with lower sensitivity can miss ACN, whereas FITs with lower specificity can increase false-positive results and unnecessary follow-up. Therefore, choice of FIT should not be considered interchangeable in FIT-based CRC screening programs.
A key limitation of the cross-sectional study is the inability to determine the sensitivity of repeated screening over a period of time, which is essential because guidelines recommend FIT testing every 2 years for CRC screening, rather than 1-time testing. Biannual FIT, regardless of the test brand, can increase both sensitivity and specificity. Data on the long-term effectiveness of different FITs are lacking.
Personalized patient selection for FIT is important. Individuals seeking a convenient test without the need for bowel preparation and time away from family/work are ideal candidates. FIT may also be the initial approach in patients at high risk for procedural and sedation complications and may help triage patients for colonoscopy in resource-limited settings and centers without the capacity for high-volume colonoscopies.
Although brand of the FIT is important, availability and associated costs may limit use. FIT sensitivity was higher for individuals with increased body mass index and lower income, which could guide initial selection for FIT. However, FIT was less sensitive in women, which may favor a colonoscopy-first approach.
Despite limitations, FIT is an important test, particularly in the context of primary care as it is the first point of contact for CRC screening. However, longitudinal studies are needed to establish the effectiveness of FIT-based CRC screening programs on long-term clinical outcomes.