title: Biologic basis and evolving role of aromatase inhibitors in the management of invasive carcinoma of the breast.
abstract: OBJECTIVE
  The most powerful predictor of the response of breast cancers to hormonal therapy is the presence of estrogen receptors in the tumor cells. Estrogen receptors are expressed in approximately 35-55% of all breast tumors but up to 80-90% of tumors from women older than 55 years.
  
  
  METHODS
  At this time, tamoxifen remains the first-line hormonal therapy for breast cancer of all stages. However, the aromatase inhibitors are evolving into an important treatment option. Aromatase inhibitors prevent the conversion of precursors (androgens) to estrogens.
  
  
  RESULTS
  On the basis of several randomized clinical trials, aromatase inhibitors have become established as the second-line therapy for postmenopausal women with advanced breast cancer progressing during tamoxifen therapy. Furthermore, very recent trials support the use of these agents as first-line therapy in place of tamoxifen.
  
  
  CONCLUSIONS
  The roles of the selective aromatase inhibitors in the prevention of breast cancer and in the neoadjuvant and adjuvant treatment of early-stage breast cancer are the focus of several planned and ongoing large-scale clinical trials. These trials will answer some of the many questions that remain regarding optimal hormonal therapy for hormone-dependent breast cancer.
authors.affiliation: Department of Surgical Oncology, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Kuerer
authors.forename: A U
authors.initials: AU
authors.lastname: Buzdar
authors.forename: S E
authors.initials: SE
authors.lastname: Singletary
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D047072:Aromatase Inhibitors; D001943:Breast Neoplasms / Q000737:chemistry / Q000188:drug therapy* / Q000473:pathology; D002986:Clinical Trials as Topic; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008593:Menopause; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D011960:Receptors, Estrogen / Q000032:analysis; D013629:Tamoxifen / Q000627:therapeutic use*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D011960:Receptors, Estrogen; D013629:Tamoxifen