GSTM1 and chronic myelogenous leukemia, BCR-ABL1 positive: Moreover, numerous studies have shown the link between the lack of enzyme activity in GSTM1 and GSTT1 and the susceptibility to develop various types of cancer, such as oral cancer, gastric cancer, bladder cancer, and CML in different ethnical groups worldwide (Bajpai et al. 2007; Sharma et al. 2013; Dunna et al. 2013; Ma et al. 2013; Dong et al. 2013; Bhat et al. 2012).