GSTM1 and renal cell carcinoma: This meta-analysis was conducted to assess whether the null genotype of GSTM1/GSTT1 and the GSTP1 A/G gene polymorphism are associated with RCC susceptibility by ethnicity, and whether there is an association between the null genotype of GSTM1/GSTT1 and clinical TNM stages in patients with RCC by ethnicity, due to the fact that the genotype distributions of the different populations might differ from each other [27, 28].