Heterozygote carriers of SNPs in CYP1A2 1545T.C, 164C.A and 740T.G; CYP2A6 47A.C; MDR1 3435T.C; NAT1 1088T.A and1095A.C;GSTA2 S112T; GSTM3 V224I andMTHFR A222V had altered risk of developinglung cancer.NAT1 fast + NAT2 fast acetylator phenotypes were at lower risk. The gene discussed is CYP2A6; the disease is cancer.