GSTM1 and cancer: We combined this threshold with the Cox model predicted cancer risk thresholds of 1%, 2% and 3% to calculate the positive predictive value, negative predictive value, sensitivity and specificity of the Cox model compared to a f‐Hb ≥ 10 and f‐Hb ≥ 40 cut off in the derivation and validation cohort (Table 3).