NFE2L2 and breast cancer: Interestingly, when the effect of combined polymorphisms was generally uniform across the three strata describing smoking status, GSTP1 Ile105Val + Val105Val and NRF2 −617CA + −617AA genotypes significantly reduced BC risk in never smokers (OR 0.29, 95 % CI 0.08–0.98), while the combined GSTM1 null and NRF2 −617CA + −617AA genotypes among current smokers were linked with significantly higher BC risk (OR 2.52, 95 % CI 1.17–5.41).