GSTM1 and colorectal carcinoma: Symptomatic diagnosis of CRC has been facilitated by the introduction of fecal immunochemical testing (FIT) in primary care, as FIT is highly sensitive for CRC.9, 12 For those presenting with lower GI symptoms, a FIT threshold of ≥10 mg haemoglobin (Hb)/g feces is currently recommended to determine who should be offered referral.13