GSTM1 and colorectal carcinoma: Repeat FIT has potential to reduce over-referral, tailor pathways for those with mildly positive FIT results, as well as reduce missed CRC diagnoses.20 However, more evidence is needed to understand thresholds at which repeat FIT is valuable, appropriate intervals between tests, and fluctuations in faecal Hb concentrations over time, in both ‘healthy’ and ‘neoplastic’ populations.22