GSTM1 and colorectal cancer: Median levels of fHb were higher in men than in women (2·4 (i.q.r. 0–23·2) versus 1·8 (0–14·8) μg Hb/g faeces respectively; P = 0·059), but the difference was not statistically significant despite a significantly higher rate of colorectal cancer in men than women across the cohort (6·8 versus 2·6 per cent; P < 0·003).