GSTM1 and colorectal carcinoma: ,4 To take a specific example, in the Scottish Bowel Screening Programme (SBoSP), after the replacement of gFOBT with FIT at a threshold of ≥80 μg Hb/g faeces, 0.09% of women (n = 307 919) and 0.15% of men (n = 279 530) screened were found to have CRC.3