title: Hypofractionated passively scattered proton radiotherapy for low- and intermediate-risk prostate cancer is not associated with post-treatment testosterone suppression.
abstract: BACKGROUND
  To investigate post-treatment changes in serum testosterone in low- and intermediate-risk prostate cancer patients treated with hypofractionated passively scattered proton radiotherapy.
  
  
  METHODS
  Between April 2008 and October 2011, 228 patients with low- and intermediate-risk prostate cancer were enrolled into an institutional review board-approved prospective protocol. Patients received doses ranging from 70 Cobalt Gray Equivalent (CGE) to 72.5 CGE at 2.5 CGE per fraction using passively scattered protons. Three patients were excluded for receiving androgen deprivation therapy (n = 2) or testosterone supplementation (n = 1) before radiation. Of the remaining 226 patients, pretreatment serum testosterone levels were available for 217. Of these patients, post-treatment serum testosterone levels were available for 207 in the final week of treatment, 165 at the six-month follow-up, and 116 at the 12-month follow-up. The post-treatment testosterone levels were compared with the pretreatment levels using Wilcoxon's signed-rank test for matched pairs.
  
  
  RESULTS
  The median pretreatment serum testosterone level was 367.7 ng/dl (12.8 nmol/l). The median changes in post-treatment testosterone value were as follows: +3.0 ng/dl (+0.1 nmol/l) at treatment completion; +6.0 ng/dl (+0.2 nmol/l) at six months after treatment; and +5.0 ng/dl (0.2 nmol/l) at 12 months after treatment. None of these changes were statistically significant.
  
  
  CONCLUSIONS
  Patients with low- and intermediate-risk prostate cancer treated with hypofractionated passively scattered proton radiotherapy do not experience testosterone suppression. Our findings are consistent with physical measurements demonstrating that proton radiotherapy is associated with less scatter radiation exposure to tissues beyond the beam paths compared with intensity-modulated photon radiotherapy.
authors.affiliation: Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA.
authors.forename: Whoon Jong
authors.initials: WJ
authors.lastname: Kil
authors.forename: Romaine C
authors.initials: RC
authors.lastname: Nichols
authors.forename: Bradford S
authors.initials: BS
authors.lastname: Hoppe
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Morris
authors.forename: Robert B
authors.initials: RB
authors.lastname: Marcus
authors.forename: William
authors.initials: W
authors.lastname: Mendenhall
authors.forename: Nancy P
authors.initials: NP
authors.lastname: Mendenhall
authors.forename: Zuofeng
authors.initials: Z
authors.lastname: Li
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Costa
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Williams
authors.forename: Randal H
authors.initials: RH
authors.lastname: Henderson
mesh_terms: D000230:Adenocarcinoma / Q000097:blood* / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D019583:Dose Fractionation, Radiation; D015536:Down-Regulation / Q000528:radiation effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D012307:Risk Factors; D013739:Testosterone / Q000097:blood*; D013997:Time Factors
chemical_list: D013739:Testosterone