Since we have demonstrated that f-Hb is affected by age and sex, with f-Hb rising with age and being higher in men than women [13], an international multi-centre collaboration led to development and validation of the FAST score, which combines f-Hb and age and sex as a single test result which might indicate individual risk of CRC and SBD [14]. This evidence concerns the gene GSTM1 and colorectal carcinoma.