title: Validation study of the accuracy of a postoperative nomogram for recurrence after radical prostatectomy for localized prostate cancer.
abstract: OBJECTIVE
  A postoperative nomogram for prostate cancer was developed at Baylor College of Medicine. This nomogram uses readily available clinical and pathologic variables to predict 7-year freedom from recurrence after radical prostatectomy. We evaluated the predictive accuracy of the nomogram when applied to patients of four international institutions.
  
  
  METHODS
  Clinical and pathologic data of 2,908 patients were supplied for validation, and 2,465 complete records were used. Nomogram-predicted probabilities of 7-year freedom from recurrence were compared with actual follow-up in two ways. First, the area under the receiver operating characteristic curve (AUC) was calculated for all patients and stratified by the time period of surgery. Second, calibration of the nomogram was achieved by comparing the predicted freedom from recurrence with that of an ideal nomogram. For patients in whom the pathologic report does not distinguish between focal and established extracapsular extension (an input variable of the nomogram), two separate calculations were performed assuming one or the other.
  
  
  RESULTS
  The overall AUC was 0.80 when applied to the validation data set, with individual institution AUCs ranging from 0.77 to 0.82. The predictive accuracy of the nomogram was apparently higher in patients who were operated on between 1997 and 2000 (AUC, 0.83) compared with those treated between 1987 and 1996 (AUC, 0.78). Nomogram predictions of 7-year freedom from recurrence were within 10% of an ideal nomogram.
  
  
  CONCLUSIONS
  The postoperative Baylor nomogram was accurate when applied at international treatment institutions. Our results suggest that accurate predictions may be expected when using this nomogram across different patient populations.
authors.affiliation: Department of Urology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Graefen
authors.forename: Pierre I
authors.initials: PI
authors.lastname: Karakiewicz
authors.forename: Ilias
authors.initials: I
authors.lastname: Cagiannos
authors.forename: Eric
authors.initials: E
authors.lastname: Klein
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Kupelian
authors.forename: David I
authors.initials: DI
authors.lastname: Quinn
authors.forename: Susan M
authors.initials: SM
authors.lastname: Henshall
authors.forename: John J
authors.initials: JJ
authors.lastname: Grygiel
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sutherland
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Stricker
authors.forename: Jean
authors.initials: J
authors.lastname: de Kernion
authors.forename: Thomas
authors.initials: T
authors.lastname: Cangiano
authors.forename: Fritz H
authors.initials: FH
authors.lastname: Schröder
authors.forename: Mark F
authors.initials: MF
authors.lastname: Wildhagen
authors.forename: Peter T
authors.initials: PT
authors.lastname: Scardino
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kattan
mesh_terms: D000328:Adult; D000368:Aged; D002138:Calibration; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009364:Neoplasm Recurrence, Local; D011237:Predictive Value of Tests; D011379:Prognosis; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery*; D012307:Risk Factors