Moreover, as shown by the androgen synthesispathway, CYP17A1 indirectly plays a role in the synthesis of estrogens,the excessive signaling of which is associated with tumor development.Androgen receptor overexpression has been noted in some breast cancers.25 It was shown that the reduction of androgenlevels was associated with the clinical improvement of patients.26 Inhibition of CYP17A1 appears to be a validapproach in the treatment of breast cancer.27 The gene discussed is CYP17A1; the disease is breast cancer.