AHR and breast cancer: In fact, several studies have shown that breast cancer patients with high AHR activity and low expression of the AHR repressor, a negative feedback regulator of AHR (Vogel and Haarmann-Stemmann, 2017[95]), experience shorter metastasis-free survival (Jeschke et al., 2019[34]; Li et al., 2014[50]; Vacher et al., 2018[91]).