Most data so far regarding the involvement of AHR in cancer have been obtained from malignant forms of the disease indicating both a cancer promoting role for AHR (Andersson et al. 2002, Moennikes et al. 2004, Feng et al. 2013) or a tumour suppressive role in cancer (Schmidt et al. 1996, Gonzales et al. 1998, Ito et al. 2004, Mulero-Navarro et al. 2006, Fritz et al. 2009, Fan et al. 2010, Spink et al. 2013). This evidence concerns the gene AHR and neoplasm.