GSTM1 and adenoma: McDonald et al.14 reported on 280 patients referred from primary care with lower GI symptoms.They found that those with significant bowel disease had a median f-Hb of 15 μg/gwhich was significantly higher than those without (p < 0.0001).Additionally, patients with low-risk adenoma had a raised median f-Hb of 13 μg/g.