title: Reversibility of androgen deprivation therapy in patients with prostate cancer.
abstract: OBJECTIVE
  We determined the duration of testosterone suppression and recovery in patients with prostate cancer treated with a hydrogel implant releasing the gonadotropin releasing hormone (GnRH) agonist histrelin or treated with a depot GnRH agonist.
  
  
  METHODS
  Luteinizing hormone (LH) and testosterone (T) responses were monitored in 3 groups. Group 1 comprised 7 patients treated with histrelin implant, which is inserted into the arm of the patient while under local anesthesia, and suppresses LH and testosterone. Following implant removal antiandrogens (flutamide or bicalutamide) were administered. Group 2 comprised 8 patients treated with long-term depot GnRH super agonists which were later withheld and patients were given bicalutamide. Group 3 consisted of 7 patients treated with bicalutamide.
  
  
  RESULTS
  In group 1 LH and T were in the castration range while implants were in place. LH increased 1 to 6 weeks after implant removal followed by an increase in T. In 7 of 8 patients in group 2, LH, T and prostate specific antigen remained suppressed for 9 months. In 6 of 7 group 3 patients LH and T increased with a decrease in prostate specific antigen.
  
  
  CONCLUSIONS
  Despite continuous prolonged T suppression for up to 3 years due to histrelin implant, LH and T increased rapidly following implant removal, indicating that suppression is reversible. In view of the 9-month suppression of LH and T after the last depot GnRH injection in 7 of 8 patients, it is possible to space GnRH agonist administration at longer intervals. However, T must be monitored to determine that suppression is maintained.
authors.affiliation: Department of Urology, Shaare Zedek Medical Center, Jerusalem, affiliated with the Faculty of Health Sciences Ben-Gurion University of the Negev, Israel. hormones@netvision.net.il
authors.forename: Alon
authors.initials: A
authors.lastname: Fridmans
authors.forename: Boris
authors.initials: B
authors.lastname: Chertin
authors.forename: Dmitry
authors.initials: D
authors.lastname: Koulikov
authors.forename: Tzina
authors.initials: T
authors.lastname: Lindenberg
authors.forename: Hadassa
authors.initials: H
authors.lastname: Gelber
authors.forename: Chavie
authors.initials: C
authors.lastname: Leiter
authors.forename: Amicur
authors.initials: A
authors.lastname: Farkas
authors.forename: Irving M
authors.initials: IM
authors.lastname: Spitz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use*; D000813:Anilides / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D005485:Flutamide / Q000627:therapeutic use*; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D009570:Nitriles; D011471:Prostatic Neoplasms / Q000097:blood* / Q000188:drug therapy*; D013739:Testosterone / Q000097:blood*; D014105:Tosyl Compounds
chemical_list: D000726:Androgen Antagonists; D000813:Anilides; D000970:Antineoplastic Agents; D009570:Nitriles; D014105:Tosyl Compounds; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D005485:Flutamide; D007986:Luteinizing Hormone; C053541:bicalutamide; C029256:histrelin