GSTM1 and colorectal carcinoma: Using test performance data from these three studies, and a CRC prevalence estimate of 3.1% to consider the outcome of testing for a hypothetical cohort of 1000 patients, the results indicate that, using the 10 μg Hb/g faeces cut-off, two CRCs would be missed and 179 unnecessary colonoscopies would be carried out (assuming that all patients with a positive FIT result receive colonoscopy and that all colonoscopies conducted in patients without CRC are considered unnecessary).