CRC incidences vary from one country to another; f-Hb distributions also vary between countries28 and even between regions of a small country like Scotland.14 In addition, in FIT-based screening programmes, different f-Hb concentration thresholds are employed to take account of national colonoscopy capacities.11,12 Thus, the issue of whether or not partitioned f-Hb thresholds should be used for women and men can only be resolved by prospective, observational studies. Here, GSTM1 is linked to colorectal carcinoma.