Faecal immunochemical test (FIT), a quantitative test for human haemoglobin in faeces, has been recommended to guide referral of patients who are considered to be at ‘low risk’ of CRC.12–14 A FIT ≥10 μg Hb/g faeces escalates the patient into the ‘2-week wait’ pathway. This evidence concerns the gene GSTM1 and colorectal carcinoma.