Previous research showed that higher fecal Hb (f‐Hb) concentrations in prior screening rounds were associated with higher detection of CRC or advanced neoplasia (AN) in subsequent screening rounds, as well as a higher probability of detecting interval CRC after negative FIT.2, 3, 4, 5, 6, 7, 8. This evidence concerns the gene GSTM1 and colorectal carcinoma.