GSTM1 and breast cancer: Furthermore, Bai et al., (2012) evaluated the prognostic role of GST gene polymorphisms among patients with breast cancer treated with neoadjuvant chemotherapy and the result showed that patients with the GSTM1 null genotype had a better survival and statistical significantly lower risk of death than patients harboring GSTM1 present genotype (HR = 0.66, 95% CI = 0.31- 0.93).