GSTM1 and colorectal carcinoma: Employing a higher cut-off for investigation will result in a smaller group of FIT positive patients with a higher PPV or prevalence for CRC, but at the expense of detecting fewer CRC; this strategy may be adopted when endoscopy capacity is restricted or paused as occurred at the height of the current COVID-19 pandemic.25 26 The likelihood of cancer increases with increasing f-Hb concentrations (above 150 μg/g), and consequently, FIT could be used to rule-in cancer or prioritise patients for investigation.