Considering that the expression of AhR target genes in the blood, including CYP1A1 and AhRR, is also upregulated in CKD patients compared to healthy controls [58], in future studies not only fine needle aspirates from kidney tumors but also blood samples could be used to measure CYP1A1 levels, as a sensitivity marker, in patients treated with AF or 5F 203. This evidence concerns the gene CYP1A1 and chronic kidney disease.