AHR and breast cancer: With the right chemical composition breast cancers become vulnerable to treatment because they not only have a hyper-active AhR pathway (Vacher et al., 2018), as a likely legacy of exposure to environmental carcinogens, but they also have inherently high SULT1A1 activity (Mercer et al., 2009; Huang et al., 2014), due to its role in the metabolism of estrogens and environmental compounds (Mercer et al., 2009; Jiang et al., 2010).