Hemoglobin (Hb) concentration in fecal immunochemical test (FIT) results during the first round of colorectal cancer (CRC) screening is an independent predictor of risk of advanced neoplasia (AN) and might be used in designing personalized strategies for CRC screening while reducing unnecessary repeat tests, new research indicates (Gastroenterology 2017; doi:10.1053/j.gastro.2017.07.034).
FIT tests “are invariably used in a dichotomous manner using pre-specified cutoff values,” yet fecal Hb concentrations have been linked to higher risk of AN, according to the authors.
To further explore the relationship between FIT Hb concentrations and later development of AN, the investigators analyzed data from a population-based study of 9,561 average-risk participants who were offered four rounds of FIT screening. They set the cutoff for positive FIT as ≥10 µg/G. Participants with positive FIT underwent colonoscopy. The median follow-up was 4.7 years.
Participants with two consecutive FIT Hb concentrations ≥8 µg/G had a 14-fold increased risk of AN compared to those with baseline concentrations of 0 µg/G. Multi-variate hazard ratios increased from 1.2 for participants with FIT Hb concentrations 0–2 µg/G to 8.2 for those with concentrations 8–10 µg/G. This rising cumulative incidence of AN based on elevated FIT Hb levels was more prominent for Hb concentrations between 4 µg/G and 10 µg/G.
In a summary and review of the study, Douglas Rex, MD, associate editor of NEJM Journal Watch, observed, “These results suggest that a considerable amount of useful clinical information, which could potentially be used to stratify FIT screening intervals, is available in the actual quantitative result, but this information is hidden from view to American clinicians because the test is reported as only positive or negative.”