Genome-wide studies (Gu and Wu, 2011) have identified a small correlation with a genetic predisposition to BC for N-acetyltransferase 2 (NAT2) and deletion of glutathione S-transferase (GSTM1) genes, both connected with the ability to metabolize aromatic amines and therefore related to the environmental carcinogen exposure and cigarette smoking (García-Closas et al., 2005). This evidence concerns the gene GSTM1 and breast cancer.