Anticancer drugs (doxorubicin, cyclophosphamide) commonly used in breast cancer patients are metabolized by hydroxylation enzymes (carbonyl reductase CBRs genes), semiquinone formation (NDUFS, NQO1, XDH, NOS genes), deoxyaglycone formation (POR, XDH, NQO1 genes), metabolisms enzymes phase I and phase II (cytochrome P450, ADH, and ALDH), glutathione S-transferase (GST), sulfotransferase (SULT), and membrane transporters (influx transporters SLC and efflux ABC transporters family) [22]. This evidence concerns the gene XDH and breast carcinoma.