Patients with negative FIT results in upper range still at risk for advanced neoplasia
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Key takeaways:
- Those in the upper range of negative fecal immunochemical test values were at higher risk for colorectal cancer.
- At a cutoff value of 17 µg/g, specificity and negative predictive values were 93%.
Among patients with negative fecal immunochemical tests, those with values in the upper range demonstrated higher risk for advanced neoplasia vs. those in the lower range, according to data in Annals of Internal Medicine.
“Fecal immunochemical tests for hemoglobin are increasingly used,” Tobias Niedermaier, PhD, of the German Cancer Research Center, and colleagues wrote. “Time intervals after which a negative FIT should be repeated — that is, annual or biennial FIT screening, or even longer intervals among persons at low risk — are debated. Risk stratification could be done by quantifying fecal hemoglobin concentration.”
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Researchers conducted a dose-response analysis to determine the association between fecal hemoglobin concentrations and presence of advanced neoplasia — colorectal cancer or advanced adenoma — among individuals undergoing screening colonoscopy.
They enrolled 7,398 participants, aged 51 to 79 years, with no history of CRC or inflammatory bowel disease who underwent quantitative FIT testing prior to colonoscopy between November 2008 and December 2020. Of those, 90% had fecal hemoglobin concentrations below the recommend FIT cutoff value of 17 µg/g.
Researchers further stratified participants according to hemoglobin concentration, from less than 1.7 µg/g to more than 45 µg/g and several ranges in between, as well as sex and age. The studied outcome was prevalence of any advanced neoplasia and of large neoplasia (≥ 1 cm).
Results showed 41% of participants had hemoglobin concentrations less than 1.7 µg/g and 81% had concentrations less than 8 µg/g; 10% had concentrations greater than 17 µg/g. Further, prevalence of advanced neoplasia increased from 6% among those with concentrations less than 1.7 µg/g to 22% in the highest group of FIT-negative results and up to 51% among those with FIT-positive results.
Researchers noted that positivity was 9.9%, sensitivity and positive predictive values were 39%, and specificity and negative predictive values were 93% when a FIT cutoff value of 17 µg/g was used.
“Our study and previous studies indicate that those in the upper range of negative FIT values are at higher risk for CRC than those in the lower range,” Niedermaier and colleagues wrote. “Despite increased complexity, this suggests a benefit from personalized screening intervals.”
They continued: “Our results may help to develop risk-adapted FIT-based screening whose (cost-)effectiveness should be evaluated by modeling studies and screening trials.”
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