In this study, we have analyzed the expression of AhR in a series of diffuse and intestinal gastric tumors, as well as the expression of xenobiotic metabolic enzymes such as cytochromes P450 (CYP1A1 and CYP1B1) and a large panel of genes known to be regulated by AhR in several cancers. This evidence concerns the gene CYP1B1 and cancer.