Androstenedione is a precursor of both estrogens and androgens, and all intermediates of both ∆4 and ∆5 pathways as well as CYP17A1 enzyme can serve as drug targets in the treatment of hormone-sensitive cancers such as prostate cancer (PCa) and breast cancer (BC) [51]. The gene discussed is CYP17A1; the disease is Familial prostate cancer.