title: Post-treatment prostate biopsies in the era of three-dimensional conformal radiotherapy: what can they teach us?
abstract: BACKGROUND
  The ability to discriminate between therapeutic success and failure after radiotherapy (RT) for prostate cancer (PCa) remains a clinical challenge. Post-treatment biopsies would seem ideal for evaluating innovations such as dose escalation protocols or combination treatments involving brachytherapy or hormones.
  
  
  OBJECTIVE
  Correlate post-treatment biopsy results with prostate-specific antigen (PSA) and clinical outcome in PCa patients treated with three-dimensional conformal radiotherapy (3DCRT) in a dose-escalation study.
  
  
  METHODS
  This study included 160 patients with clinical stage T1c to T3b PCa treated between 1995 and 2005 in Hospital Universitario la Princesa with 3DCRT who consented to and underwent a transrectal ultrasound (TRUS)-guided prostate biopsy 24-36 mo after RT. The median follow-up was 78 mo (range 27-171 mo).
  
  
  METHODS
  The median radiation dose was 74 gray (Gy; range 66.0-84.1). Risk-adapted short-term androgen deprivation (STAD) and long-term androgen deprivation (LTAD) were associated in 25 and 106 patients, respectively. Right and left systematic biopsies were carried out by the same urologist and were examined by a genitourinary pathologist.
  
  
  METHODS
  Biochemical disease-free survival (bDFS) according to American Society for Therapeutic Radiology and Oncology (ASTRO) 1997 and Phoenix definition criteria as well as histologic control using post-treatment prostate biopsies.
  
  
  RESULTS
  Twenty-one percent of patients (34 of 160) had post-treatment-positive biopsies (PB). The 5-yr bDFS according to the Phoenix definition was 87%, 65%, and 92% for the whole series (PB and negative biopsies [NB] patients, respectively [p<0.001]). Multivariate analysis showed that biopsy status at 24-36 mo was an independent predictor of bDFS (p<0.0005) and of clinical failure-free survival (p=0.043).
  
  
  CONCLUSIONS
  The results of the present study show a strong correlation between a post-treatment PB and the 5-yr probability of bDFS, confirming that PSA control can be an adequate surrogate for local control, as assessed by post-treatment biopsies.
authors.affiliation: Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain. azapatero.hlpr@salud.madrid.org
authors.forename: Almudena
authors.initials: A
authors.lastname: Zapatero
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mínguez
authors.forename: Santiago
authors.initials: S
authors.lastname: Nieto
authors.forename: Carmen
authors.initials: C
authors.lastname: Martín de Vidales
authors.forename: Feliciano
authors.initials: F
authors.lastname: García-Vicente
mesh_terms: D000368:Aged; D001707:Biopsy, Needle; D006801:Humans; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D017430:Prostate-Specific Antigen