title: Rise in serum PSA of 1.5 ng/mL above 24-month nadir after external beam radiotherapy is predictive of biochemical failure.
abstract: OBJECTIVE
  To determine whether a rise in the serum prostate-specific antigen (PSA) concentration 24 months or later after completion of external beam radiotherapy (EBRT) for prostate cancer could predict for biochemical failure.
  
  
  METHODS
  We evaluated the records of 1006 patients who had undergone full-dose EBRT alone as primary treatment for T1-T4NxM0 prostate cancer at our institution between April 1987 and January 1998. Patients who had biochemical failure--as determined by the American Society for Therapeutic Radiology and Oncology (ASTRO) definition--prior to 24 months after EBRT were excluded. PSA increases of four different magnitudes (0.5, 0.8, 1.0, and 1.5 ng/mL above the 24-month nadir) were evaluated for their ability to predict ASTRO-defined biochemical failure.
  
  
  RESULTS
  A total of 745 patients met the analysis criteria. The rate of ASTRO-defined biochemical failure in patients with a PSA increase of 0.5, 0.8, 1.0, and 1.5 ng/mL above the 24-month nadir was 56%, 64%, 66%, and 71%, respectively. An increase of 1.5 ng/mL or more had a sensitivity of 80% and a specificity of 88% in the prediction of biochemical failure, with an accuracy of 86%.
  
  
  CONCLUSIONS
  A PSA increase of 1.5 ng/mL or more above the 24-month nadir can be used to predict for ASTRO-defined failure after EBRT and may be used to identify patients at risk early-on.
authors.affiliation: Department of Urology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Ashish M
authors.initials: AM
authors.lastname: Kamat
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Rosser
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Levy
authors.forename: Ramsey
authors.initials: R
authors.lastname: Chichakli
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Lee
authors.forename: Min Rex
authors.initials: MR
authors.lastname: Cheung
authors.forename: Louis L
authors.initials: LL
authors.lastname: Pisters
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D017211:Treatment Failure
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen