title: Does salvage radiation therapy change the biology of recurrent prostate cancer based on PSA doubling times? Results from the SEARCH database.
abstract: OBJECTIVE
  To investigate whether salvage radiation therapy (SRT) may promote prostate cancer (PCa) transformation to more aggressive phenotypes. To accomplish that, we identified men who underwent SRT after radical prostatectomy for PCa and failed SRT. PSA doubling time (PSADT) was used as a surrogate endpoint for cancer aggressiveness. We compared PSADT calculated before start of SRT and after SRT failure.
  
  
  METHODS
  Of 287 men in the SEARCH database since 1988 who underwent SRT, we detected 78 with SRT failure defined as PSA ≥ 0.2 ng/mL above the post-SRT nadir. Of these, 39 had PSADT available before and after SRT, which was compared using Wilcoxon's paired test with men serving as their own controls. We tested predictors of PSADT change using multivariable logistic regression.
  
  
  RESULTS
  There were no differences in PSADT before and after SRT (10.2 vs 12.6 months; P = .46). However, in some individual cases, large changes were observed. Only seminal vesicle invasion showed a trend towards an association with a shorter post-SRT PSADT relative to the pre-SRT PSADT (P = .13).
  
  
  CONCLUSIONS
  Overall, the PSADT after and before SRT were statistically identical, suggesting that after SRT failure, PCa does not emerge with more aggressive biological features. Further studies are needed to identify predictors and the clinical relevance of individual PSADT changes noted in our study.
authors.affiliation: Division of Urologic Surgery, Department of Surgery, Duke University School of Medicine, Durham, NC 27710, USA. roberto.muller@duke.edu
authors.forename: Roberto L
authors.initials: RL
authors.lastname: Muller
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Presti
authors.forename: William J
authors.initials: WJ
authors.lastname: Aronson
authors.forename: Martha K
authors.initials: MK
authors.lastname: Terris
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kane
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Amling
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Freedland
mesh_terms: D000368:Aged; D018450:Disease Progression; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D012189:Retrospective Studies; D016879:Salvage Therapy; D012669:Seminal Vesicles / Q000473:pathology; D018709:Statistics, Nonparametric; D017211:Treatment Failure
chemical_list: D017430:Prostate-Specific Antigen