GSTM1 and colorectal carcinoma: Contemporary meta-analyses estimate the single-FIT sensitivity for CRC to be 67% in screening programmes with a positivity threshold of 40 μg haemoglobin per gram (Hb/g) or less [3], and between 88 and 90% at 10 μg Hb/g in symptomatic cohorts [3,4,5].