GSTM1 and lung cancer: In the present study, the significant interaction between cigarette smoking and CY1A1 or GSTM1 variants is consistent with the results of previous pooled analysis that the stronger association between the CYP1A1 MspI or GSTM1 null and lung cancer was found among smokers [22], but a non significant elevated risk of interaction between GSTM1 null genotype and lung cancer was reported among Asian by Benhamou and co-workers [23].