title: Brachytherapy boost and cancer-specific mortality in favorable high-risk versus other high-risk prostate cancer.
abstract: OBJECTIVE
  Recent retrospective data suggest that brachytherapy (BT) boost may confer a cancer-specific survival benefit in radiation-managed high-risk prostate cancer. We sought to determine whether this survival benefit would extend to the recently defined favorable high-risk subgroup of prostate cancer patients (T1c, Gleason 4 + 4 = 8, PSA < 10 ng/ml or T1c, Gleason 6, PSA > 20 ng/ml).
  
  
  METHODS
  We identified 45,078 patients in the Surveillance, Epidemiology, and End Results database with cT1c-T3aN0M0 intermediate- to high-risk prostate cancer diagnosed 2004-2011 treated with external beam radiation therapy (EBRT) only or EBRT plus BT. We used multivariable competing risks regression to determine differences in the rate of prostate cancer-specific mortality (PCSM) after EBRT + BT or EBRT alone in patients with intermediate-risk, favorable high-risk, or other high-risk disease after adjusting for demographic and clinical factors.
  
  
  RESULTS
  EBRT + BT was not associated with an improvement in 5-year PCSM compared to EBRT alone among patients with favorable high-risk disease (1.6% vs. 1.8%; adjusted hazard ratio [AHR]: 0.56; 95% confidence interval [CI]: 0.21-1.52, p = 0.258), and intermediate-risk disease (0.8% vs. 1.0%, AHR: 0.83, 95% CI: 0.59-1.16, p = 0.270). Others with high-risk disease had significantly lower 5-year PCSM when treated with EBRT + BT compared with EBRT alone (3.9% vs. 5.3%; AHR: 0.73; 95% CI: 0.55-0.95; p = 0.022).
  
  
  CONCLUSIONS
  Brachytherapy boost is associated with a decreased rate of PCSM in some men with high-risk prostate cancer but not among patients with favorable high-risk disease. Our results suggest that the recently-defined "favorable high-risk" category may be used to personalize therapy for men with high-risk disease.
authors.affiliation: Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, MA.
authors.forename: Vinayak
authors.initials: V
authors.lastname: Muralidhar
authors.affiliation: Department of Radiation Oncology, Stanford School of Medicine, Stanford, CA.
authors.forename: Michael
authors.initials: M
authors.lastname: Xiang
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham and Women's Hospital, Boston, MA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Orio
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham and Women's Hospital, Boston, MA.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Martin
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham and Women's Hospital, Boston, MA.
authors.forename: Clair J
authors.initials: CJ
authors.lastname: Beard
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI.
authors.forename: Felix Y
authors.initials: FY
authors.lastname: Feng
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center, Houston, USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Hoffman
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham and Women's Hospital, Boston, MA.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Nguyen
keywords: brachytherapy; favorable high-risk prostate cancer; high-risk prostate cancer; risk stratification