title: Prostate-specific antigen response after short-term hormone therapy plus external-beam radiotherapy and outcome in patients treated on Radiation Therapy Oncology Group study 9413.
abstract: BACKGROUND
  The objective of this study was to assess the impact of a prostate-specific antigen (PSA) complete response (PSA-CR), measured at the end of external-beam radiotherapy and short-term hormone therapy, on treatment outcomes.
  
  
  METHODS
  The phase 3 Radiation Therapy Oncology Group 9413 trial, as part of its original protocol, used the assessment of PSA-CR (ie, PSA ≤0.3 ng/mL) at the end of short-term HT as a secondary endpoint. Short-term HT consisted of futamide plus a lutenizing hormone-releasing hormone agonist for 4 months. The Kaplan-Meier method was used to estimate overall survival (OS) and disease-free survival. Cumulative incidence was used to estimate biochemical failure, distant metastasis, and disease-specific survival. Univariate and multivariate analyses were performed to correlate PSA-CR after short-term hormone therapy with all endpoints, and the following variables were considered for analysis: PSA at baseline, Gleason score, treatment arm, age, and baseline testosterone status. Phoenix consensus definition was used to define PSA failure.
  
  
  RESULTS
  For 1070 evaluable patients, the median PSA at the end of short-term hormone therapy was 0.2 ng/mL. In total, 744 patients (70%) had a PSA-CR. At a median follow-up of 7.2 years, failure to obtain a PSA-CR was associated significantly with worse disease-specific survival (P = .0003; hazard ratio [HR], 2.03; 95% confidence interval [CI], 1.38-2.97), with worse disease-free survival (P = .003; HR, 1.28; 95% CI, 1.09-1.50), and with a higher incidence of distant metastasis (P = .0002; HR, 1.92; 95% CI, 1.37-2.69) and biochemical failure (P < .0001; HR, 1.57; 95% CI, 1.29-1.91). Other factors that were associated with worse disease-specific survival were Gleason scores from 8 to 10 (P = .0002; HR, 3.06; 95% CI, 1.71-5.47) and PSA levels >20 ng/mL (P = .04; HR, 1.55; 95% CI, 1.02-2.30).
  
  
  CONCLUSIONS
  The current results indicated that failure to obtain a PSA-CR (PSA ≤0.3 ng/mL) after short-term hormone therapy and external-beam radiotherapy appears to be an independent predictor of unfavorable outcomes and could help identify patients who may benefit from the addition of long-term androgen ablation.
authors.affiliation: Radiation Oncology, McGill University Health Centre, Montreal, Quebec, Canada. fabio.cury@muhc.mcgill.ca
authors.forename: Fabio L
authors.initials: FL
authors.lastname: Cury
authors.forename: Daniel
authors.initials: D
authors.lastname: Hunt
authors.forename: Mack
authors.initials: M
authors.lastname: Roach
authors.forename: William
authors.initials: W
authors.lastname: Shipley
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Gore
authors.forename: I-Chow
authors.initials: IC
authors.lastname: Hsu
authors.forename: Robert E
authors.initials: RE
authors.lastname: Krisch
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Seider
authors.forename: Howard
authors.initials: H
authors.lastname: Sandler
authors.forename: Colleen
authors.initials: C
authors.lastname: Lawton
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000008:administration & dosage; D018572:Disease-Free Survival; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy*; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D016896:Treatment Outcome
chemical_list: D000726:Androgen Antagonists; D007987:Gonadotropin-Releasing Hormone; D017430:Prostate-Specific Antigen