GSTM1 and lung cancer: In addition, exclusion of the study of Cao YF et al. [45] resulted in a statistically significant association between the combined effects of GSTM1 and GSTT1 polymorphisms and lung cancer risk in Asians (− − vs. + +: OR = 1.91, 95% CI: 1.34 to 2.74, P < 0.001).