title: Prostate specific antigen doubling time as a surrogate end point for prostate cancer specific mortality following radical prostatectomy or radiation therapy.
abstract: OBJECTIVE
  A short posttreatment prostate specific antigen (PSA)-doubling time (DT) following radical prostatectomy or radiation therapy was evaluated as a surrogate end point for prostate cancer specific mortality (PCSM).
  
  
  METHODS
  Baseline, treatment and followup information was compiled on a cohort of 8,669 patients with prostate cancer treated with surgery (5,918) or radiation (2,751) from January 1, 1988 to January 1, 2002 for clinical stage T1c-4NxMo prostate cancer, forming the study cohort. Cox regression analysis was used to test whether Prentice criteria were violated in this cohort.
  
  
  RESULTS
  After PSA defined recurrence PSA-DT less than 3 months and the specific value of PSA-DT at 3 months or greater were statistically significantly associated with time to PCSM and with time to all cause mortality after PSA defined recurrence (each Cox p <0.001). Treatment received was not statistically significant associated with time to PCSM following PSA defined recurrence in patients with PSA-DT less than 3 months (Cox p = 0.90) and in patients with PSA-DT 3 months or greater (Cox p = 0.28). Furthermore, after PSA defined recurrence PSA-DT less than 3 months was statistically significantly associated with PCSM (HR 19.6, 95% CI 12.5 to 30.9).
  
  
  CONCLUSIONS
  Posttreatment PSA-DT appears to be a surrogate end point for PCSM following surgery or radiation therapy. We recommend that consideration should be given to enrollment onto a clinical trial and/or initiating androgen suppression therapy at the time of PSA defined recurrence when PSA-DT is less than 3 months to delay the imminent sequelae of metastatic bone disease.
authors.affiliation: Department of Radiation Oncology, Brigham and Women's Hospital and Dana Farber Cancer Institute, Boston, Massachusetts 02215, USA. adamico@lroc.harvard.edu
authors.forename: Anthony V
authors.initials: AV
authors.lastname: D'Amico
authors.forename: Judd
authors.initials: J
authors.lastname: Moul
authors.forename: Peter R
authors.initials: PR
authors.lastname: Carroll
authors.forename: Leon
authors.initials: L
authors.lastname: Sun
authors.forename: Deborah
authors.initials: D
authors.lastname: Lubeck
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Chen
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D003131:Combined Modality Therapy; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood* / Q000401:mortality* / Q000601:surgery / Q000628:therapy*; D012044:Regression Analysis; D018570:Risk Assessment; D016019:Survival Analysis
chemical_list: D018931:Antineoplastic Agents, Hormonal; D017430:Prostate-Specific Antigen