The odd ratio estimated for smokers in lung cancer cases with association to GSTT1 null genotypes (OR=4.773, 95%CI=1.939-11.751, p<0.001) found statistically significant whereas no association found with GSTM1 (OR=2.00, 95%CI=0.166-1.26, p-value=0.123, Table 4). This evidence concerns the gene GSTM1 and lung cancer.