After the first round, participants in the category with the highest f‐Hb concentrations (>40‐46.9 μg Hb/g feces) had an OR of 16.9 (95% CI 13.9‐20.3) for detection of interval CRC compared with participants with unmeasurable f‐Hb concentration, when adjusted for sex‐ and age‐differences (Model 1; Table 3). This evidence concerns the gene GSTM1 and colorectal carcinoma.