title: Relative potencies of anastrozole and letrozole to suppress estradiol in breast cancer patients undergoing ovarian stimulation before in vitro fertilization.
abstract: BACKGROUND
  Breast cancer patients undergoing controlled ovarian hyperstimulation (COH) for embryo or oocyte cryopreservation should be induced by the method that leads to the least increase in estradiol (E(2)) levels.
  
  
  OBJECTIVE
  The aim of the study was to determine the potency of anastrozole to suppress serum E(2) levels in breast cancer patients undergoing COH.
  
  
  METHODS
  A prospective sequential cohort study was conducted in an academic center for reproductive medicine between May 2003 and November 2005 for letrozole and between December 2005 and April 2006 for anastrozole.
  
  
  METHODS
  Breast cancer patients presenting for fertility preservation participated in the study.
  
  
  METHODS
  COH using FSH and letrozole (n = 47) or anastrozole (n = 7) was followed by oocyte retrieval and embryo cryopreservation.
  
  
  METHODS
  Serum E(2) levels, area under the curve for E(2), and outcomes of COH cycles were measured.
  
  
  RESULTS
  There were no significant differences between the two groups regarding length of stimulation, total gonadotropin dose, number of follicles larger than 17 mm, and the lead follicle size on human chorionic gonadotropin (hCG) day and number of embryos cryopreserved. The mean E(2) levels on the day of hCG and post-hCG days were higher in the anastrozole group compared to the letrozole group (1325.89 +/- 833.17 and 2515.07 +/- 1368.52 vs. 427.78 +/- 278.24 and 714.38 +/- 440.83 pg.d/ml; P < or = 0.01), respectively, even when anastrozole dose was increased up to 10 mg/d. The mean area under the curve was significantly higher in the anastrozole group compared to the letrozole group (4402.93 +/- 1526.7 vs. 1287.48 +/- 732.17 pg.d/ml; P <0.004).
  
  
  CONCLUSIONS
  Breast cancer patients who underwent ovarian stimulation with anastrozole had a significantly higher exposure to E(2) than those who were stimulated with letrozole.
authors.affiliation: Department of Obstetrics and Gynecology, Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: Amr A
authors.initials: AA
authors.lastname: Azim
authors.forename: Maria
authors.initials: M
authors.lastname: Costantini-Ferrando
authors.forename: K
authors.initials: K
authors.lastname: Lostritto
authors.forename: Kutluk
authors.initials: K
authors.lastname: Oktay
mesh_terms: D000328:Adult; D000077384:Anastrozole; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000009:adverse effects; D001943:Breast Neoplasms / Q000097:blood*; D015925:Cryopreservation; D004958:Estradiol / Q000097:blood*; D005260:Female; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D000077289:Letrozole; D007986:Luteinizing Hormone / Q000097:blood; D009570:Nitriles / Q000008:administration & dosage* / Q000009:adverse effects; D009865:Oocytes; D010062:Ovulation Induction / Q000379:methods*; D011446:Prospective Studies; D014230:Triazoles / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D018931:Antineoplastic Agents, Hormonal; D009570:Nitriles; D014230:Triazoles; D000077384:Anastrozole; D004958:Estradiol; D000077289:Letrozole; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone