Prior faecal haemoglobin concentrations can help predict risk of future CRC, advanced neoplasia

Prior faecal haemoglobin (F-Hb) concentrations are prognostic of the risk of developing colorectal cancer (CRC) or advanced neoplasia (AN), according to a study. When added to age and sex, prior F-Hb concentrations can accurately identify individuals at risk of the said diseases.

The study used data from the Dutch biennial faecal immunochemical test (FIT)-based screening programme during 2014–2018 and included 265,881 participants completing three rounds of FIT with negative test results (F-Hb <47 µg Hb/g faeces) in rounds 1 and 2. The participants underwent a follow-up colonoscopy after a positive FIT (F-Hb ≥47 µg Hb/g faeces) in round 3.

Researchers evaluated prognostic models for detecting advanced neoplasia and CRC in round 3, with predictors including participant age, sex, F-Hb in rounds 1 and 2, and categories/combinations/nonlinear transformations of F-Hb.

Of the participants, 8,806 (3.3 percent) had a positive FIT result in round 3, including 3,254 (1.2 percent) with AN and 557 (0.2 percent) with cancer. F-Hb concentrations in rounds 1 and 2 were strongly predictive of the outcome, with adjusted ORs of up to 9.4 (95 percent confidence interval [CI], 7.5–11.7) for the highest F-Hb category.

A model including age, sex, and discrete F-Hb categories performed best. The predicted risk matched the observed risk for most participants (calibration intercept, −0.008 to −0.099) and was able to differentiate between participants with and without AN or CRC (C-statistics, 0.78, 95 percent CI, 0.77–0.79 and 0.73, 95 percent CI, 0.71–0.75, respectively). Across the participants, the predicted risk varied between 0.4 percent and 36.7 percent for AN and between 0.0 percent and 5.5 percent for CRC.

External validation of the model showed similar predictive accuracy for AN (C-statistic, 0.77, 95 percent CI, 0.66–0.87) and CRC (C-statistic, 0.78, 95 percent CI, 0.66–0.91).