It is known that a relationship between BC risk and genetic polymorphisms of enzymes involved in the generation and removal of iron-mediated ROS such as Nrf2 (nuclear factor erythroid 2–related factor 2), NQO1 (NAD (P) H Quinone Dehydrogenase 1), NOS3 (nitric oxide synthase 3, also known as endothelial NOS) and HO-1 (heme oxygenase 1) exists and can potentially be used as a pharmacological target for cancer therapies. The gene discussed is NOS3; the disease is breast cancer.