title: Variation in serum prostate-specific antigen levels in men with prostate cancer managed with active surveillance.
abstract: OBJECTIVE
  To describe fluctuations in prostate-specific antigen (PSA) levels in men managed with active surveillance (AS) to determine if a single PSA increase is a consistent measure to use to trigger intervention.
  
  
  METHODS
  We evaluated data on 541 patients undergoing AS between 1995 and 2011. PSA variation was described by studying the Kaplan-Meier probability of patients' PSA levels reaching 4 or 7 ng/mL, falling below those thresholds, and then rising to those thresholds again. We also examined PSA variation by calculating the Kaplan-Meier probability of a PSA change followed by an equal or greater change in the opposite direction.
  
  
  RESULTS
  We analysed data on 541 patients undergoing AS with a median (interquartile range [IQR]) of 8 (6-12) PSA measurements and undergoing AS for a median (IQR) of 4 (2-6) years. The 5-year estimate of the probability of reaching a threshold PSA of 7 ng/mL was 40% (95% confidence interval [CI] 35-46%) and the 5-year estimate of subsequently falling below this threshold was 90% (95% CI 82-95%). The 5-year estimate of a PSA direction change was 95% (95% CI 93-97%) overall and 56% (95% CI 51-61%) for PSA direction changes of ≥1 ng/mL.
  
  
  CONCLUSIONS
  We observed a high probability of variability in PSA levels for patients on AS. The probability of changes in PSA, defined by an increase to the specified thresholds or a rise >1 ng/mL within 6 months and subsequent decrease of equal or greater value on a subsequent measurement, increases over time; therefore, a single change in PSA level is not a reliable endpoint for patients on AS.
authors.affiliation: Urology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA. ehdaieb@mskcc.org.|Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA. ehdaieb@mskcc.org.
authors.forename: Behfar
authors.initials: B
authors.lastname: Ehdaie
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Bing Ying
authors.initials: BY
authors.lastname: Poon
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Sjoberg
authors.affiliation: Urology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA.|Urology Service, Fundacion Arturo Lopez Perez, Santiago, Chile.
authors.forename: Pedro
authors.initials: P
authors.lastname: Recabal
authors.affiliation: Urology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Laudone
authors.affiliation: Urology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA.
authors.forename: Karim
authors.initials: K
authors.lastname: Touijer
authors.affiliation: Urology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA.
authors.forename: James
authors.initials: J
authors.lastname: Eastham
authors.affiliation: Urology Service, Sidney Kimmel Center for Prostate and Urologic Cancers, New York, NY, USA.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Scardino
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000628:therapy*; D012189:Retrospective Studies; D057832:Watchful Waiting
chemical_list: D017430:Prostate-Specific Antigen
keywords: PSA; active surveillance; prostate cancer; prostate specific antigen