title: Low incidence of new biochemical hypogonadism after intensity modulated radiation therapy for prostate cancer.
abstract: OBJECTIVE
  To evaluate serum testosterone and the incidence of biochemical hypogonadism in men treated with intensity modulated radiation therapy (IMRT) for prostate cancer.
  
  
  METHODS
  Serum testosterone was evaluated prospectively in 51 men at pretreatment and at 6-month time points for 2 years posttreatment with IMRT for prostate cancer. Forty-one patients (80%) were treated with definitive intent and 10 patients with postprostatectomy radiation to median total doses of 7380 cGy and 6480 cGy, respectively. No patients received hormone therapy within 12 months of any serum testosterone value. Biochemical hypogonadism was defined as a total serum testosterone level ≤ 300 ng/dL. Incidental testicular dose was calculated using planning software when computed tomography information was available (n = 21) and using a published method of estimation when not available (n = 24), and was available for 45 patients.
  
  
  RESULTS
  A statistically significant decrease in testosterone, though small in magnitude, was seen at 6 months after completion of therapy, with no significant difference by 1 year after completion of therapy. There was no increase in biochemical hypogonadism after IMRT. Below-normal pretreatment testosterone was not associated with a transient decrease. Estimated cumulative testicular dose, including dose from daily imaging, was not associated with a change in testosterone, nor was radiation therapy prescription dose or treatment intent (postoperative vs definitive).
  
  
  CONCLUSIONS
  The mild transient decrease in serum testosterone following IMRT monotherapy for prostate cancer is not associated with new biochemical hypogonadism.
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Markovina
authors.affiliation: Hospital São Lucas, Pontifício Universidade Católica de Porto Alegre, Brasil.
authors.forename: Débora Cristina
authors.initials: DC
authors.lastname: Weschenfelder
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
authors.forename: Hiram
authors.initials: H
authors.lastname: Gay
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
authors.forename: Audrey
authors.initials: A
authors.lastname: McCandless
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
authors.forename: Bethany
authors.initials: B
authors.lastname: Carey
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
authors.forename: Todd
authors.initials: T
authors.lastname: DeWees
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri.
authors.forename: Nels
authors.initials: N
authors.lastname: Knutson
authors.affiliation: Department of Radiation Oncology and Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri. Electronic address: jmichalski@radonc.wustl.edu.
authors.forename: Jeff
authors.initials: J
authors.lastname: Michalski
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007006:Hypogonadism / Q000097:blood / Q000209:etiology*; D015994:Incidence; D007610:Kallikreins / Q000097:blood; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000097:blood / Q000209:etiology*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen