GSTM1 and breast cancer: Moreover, candidate association studies have unveiled that the gene polymorphisms of N-acetyltransferase (NAT-2) and glutathione S transferases (GSTM1 and GSTT1) (detoxifying arylamines and polycyclic hydrocarbons), and of arsenic (+3 oxidation state) methyltransferase (AS3MT) are associated with a higher risk of BC (6, 8).