title: The role of androgen deprivation therapy on biochemical failure and distant metastasis in intermediate-risk prostate cancer: effects of radiation dose escalation.
abstract: BACKGROUND
  To determine whether the effect of androgen deprivation therapy (ADT) on the risk of biochemical failure varies at different doses of radiation in patients treated with definitive external beam radiation for intermediate risk prostate cancer (IRPC).
  
  
  METHODS
  This study included 1218 IRPC patients treated with definitive external beam radiation therapy to the prostate and seminal vesicles from June 1987 to January 2009 at our institution. Patient, treatment, and tumor information was collected, including age, race, Gleason score, radiation dose, PSA, T-stage, and months on ADT.
  
  
  RESULTS
  The median follow-up was 6 years. A total of 421(34.6%) patients received ADT, 211 (17.3%) patients experienced a biochemical failure, and 38 (3.1%) developed distant metastasis. On univariable analyses, higher PSA, earlier year of diagnosis, higher T-stage, lower doses of radiation, and the lack of ADT were associated with an increased risk of biochemical failure. No difference in biochemical failure was seen among different racial groups or with the use of greater than 6 months of ADT compared with less than 6 months. On multivariate analysis, the use of ADT was associated with a lower risk of biochemical failure than no ADT (HR, 0.599; 95% CI, 0.367-0.978; P<0.04) and lower risk of distant metastasis (HR, 0.114; 95% CI, 0.014-0.905; P=0.04).
  
  
  CONCLUSIONS
  ADT reduced the risk of biochemical failure and distant metastasis in both low- and high dose radiation groups among men with intermediate-risk PCa. Increasing the duration of ADT beyond 6 months did not reduce the risk of biochemical failures. Better understanding the benefit of ADT in the era of dose escalation will require a randomized clinical trial.
authors.affiliation: Department of Radiology, Baylor College of Medicine, One Baylor Plaza, MS: BCM360 Room 165B, Houston, TX, 77030, USA. Michelle.Ludwig@bcm.edu.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Ludwig
authors.affiliation: Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA. dakuban@mdanderson.org.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Kuban
authors.forename: Sara S
authors.initials: SS
authors.lastname: Strom
authors.affiliation: Division of Epidemiology, Human Genetics, and Environmental Sciences, University of Texas School of Public Health, Houston, TX, 77030, USA. Xianglin.l.du@uth.tmc.edu.
authors.forename: Xianglin L
authors.initials: XL
authors.lastname: Du
authors.affiliation: Division of Epidemiology, Human Genetics, and Environmental Sciences, University of Texas School of Public Health, Houston, TX, 77030, USA. David.s.lopez@uth.tmc.edu.
authors.forename: David S
authors.initials: DS
authors.lastname: Lopez
authors.affiliation: Division of Biostatistics, University of Texas School of Public Health, Houston, TX, 77030, USA. Jose-miguel.yamal@uth.tmc.edu.
authors.forename: Jose-Miguel
authors.initials: JM
authors.lastname: Yamal
mesh_terms: D000230:Adenocarcinoma / Q000556:secondary / Q000628:therapy*; D017668:Age of Onset; D000368:Aged; D000726:Androgen Antagonists / Q000627:therapeutic use*; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000628:therapy*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies
chemical_list: D000726:Androgen Antagonists; D017430:Prostate-Specific Antigen