GSTM1 and lung cancer: Genotype combinations of GSTM1 (positive) /GSTT1 (null) (OR=1.5, 95% CI=0.887-2.5360) and GSTM1 (null)/GSTT1 (positive) (OR=1.174, 95%CI=0.670-2.057) (Table 5) were associated with lung cancer risk but statistically non significant.