In fact, recent studies have shown that AhR is overexpressed and/or constitutively active, even in the absence of environmental ligands, in several human tumors such as breast, liver, lung, gastric, pancreatic, prostate, urothelial, ovarian cancers, T-cell leukemia, glioma and medulloblastoma [6,7] and that it can act as a promoter [8] or a suppressor of cancers growth [9,10]. Here, AHR is linked to cancer.