GSTA1 and breast cancer: We also observed significantly increased BC risk associated with GSTM1 null and GSTA1 −69CT + −69TT genotype (OR 1.56, 95 % CI 1.08–2.26), which is in agreement with results from the previous study conducted in Serbia, where smoking carriers of those variant genotypes exhibited high risk of BC (OR 2.00, 95 % CI 0.83–4.81) (Matic et al. 2013).