CYP2A6 and neoplasm: In univariate analysis, the CYP2A6 genotype was significantly associated with tumour response rates; 66.7% for W/W patients vs 58.3% for W/V other than *1/*4 vs 32.3% for V/V or *1/*4 (Pearson χ2-test, P=0.019; trend test, P=0.008) (Table 3).