Hemoglobin Concentration Is Related to Risk for Colorectal Neoplasia, Even in People with Negative FIT

It is well known that higher concentrations of hemoglobin (Hgb) in stool are associated with a greater risk for colorectal cancer. In the United States, fecal immunochemical test (FIT) results are reported only as positive or negative, based on the cut-off level selected. The Multi-Society Task Force on Colorectal Cancer recommends a cut-off of 20 µg Hgb/g feces. Higher cut-offs are associated with lower sensitivity, higher specificity, and higher positive-predictive value.

In the current study, Dutch investigators used a cut-off of 10 µg Hgb/g feces in examining the long-term risk for advanced neoplasia among approximately 7500 screened residents whose FIT tests were negative (<10 µg Hgb/g feces), according to the amount of Hgb in the stool. At 5 years after the baseline FIT, those with an Hgb concentration of 8 to 10 µg/g had an eightfold higher risk for advanced neoplasia compared with those with 0 µg/g (33% vs. 5%), with a gradient of risk for intermediate concentrations.