title: Routine prostate biopsies following radiotherapy for prostate cancer: results for 226 patients.
abstract: OBJECTIVE
  To determine the time course of histologic resolution of prostate cancer following radiotherapy (RT) and to correlate biopsy results with clinical outcome.
  
  
  METHODS
  Since July 1990, all patients treated with radical external beam RT for prostate cancer at the General Division of the Ottawa Regional Cancer Centre have had systematic transrectal ultrasound (TRUS) and TRUS-guided biopsies beginning 12 months after RT and then every 6 months until negative or until clinical failure. Thus, 226 patients have had 375 TRUS with four to seven specimens per examination. Stage distribution was T1b: 32, T1c: 11, T2a: 45, T2b: 82, T3: 50, and T4: 6. Median follow-up was 33 months.
  
  
  RESULTS
  Biopsy results were negative in 69.5% of patients by 30 months of follow-up. Thirty-two (14%) had local failure (T1b: 12.5%, T1c: 0%, T2a: 11%, T2b: 15%, T3: 18%, T4: 33%). Seven (3%) had chemical failure, and 47 (21%) had biopsy-only failure. Median follow-up for the biopsy-only failure group is only 19.5 months and mean prostate-specific antigen (PSA) is 1.0 ng/mL. Thirty-nine patients, initially with biopsy-only failure, have converted to negative biopsies at a median of 26 months. Nadir PSA for patients with local failure was 3.9 ng/mL at 14 months versus 0.7 ng/mL at 23 months for those without failure. Patients with late conversion to negative biopsy results had a later nadir PSA of 1.3 ng/mL at 27.3 months.
  
  
  CONCLUSIONS
  Routine prostate biopsy specimens after RT in an unselected population show tumor clearance that is in agreement with long-term clinical follow-up, although tumor may take more than 30 months to resolve. Nadir PSA can be used to predict outcome.
authors.affiliation: Department of Radiation Oncology, Ottawa Regional Cancer Centre, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Crook
authors.forename: G A
authors.initials: GA
authors.lastname: Perry
authors.forename: S
authors.initials: S
authors.lastname: Robertson
authors.forename: B A
authors.initials: BA
authors.lastname: Esche
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D018809:Proliferating Cell Nuclear Antigen / Q000097:blood; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000532:radiotherapy*
chemical_list: D018809:Proliferating Cell Nuclear Antigen