Epidemiological studies conducted after the “Seveso accident”, one of the best known industrial accidents, and studies on chemical workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin) [6] have revealed increased risks of developing breast cancer following exposure to TCDD, a potent ligand of the aryl hydrocarbon nuclear receptor (AhR). This evidence concerns the gene AHR and breast carcinoma.