GSTM1 and breast cancer: In the present study, we verified that the majority of breast cancer patients with the null genotype of GSTT1 were 50 years old or more (p-value = 0.021), and in a two-way association of GSTT1 and GSTM1 genotypes with age, we verified similar results: the majority of the elderly patients had both polymorphisms (p-value = 0.018).