title: External validation of the updated Briganti nomogram to predict lymph node invasion in prostate cancer patients undergoing extended lymph node dissection.
abstract: OBJECTIVE
  We aimed to test accuracy and generalizability of a recently updated nomogram to assess the probability of lymph node invasion (LNI), when applied to a different European cohort of men undergoing radical prostatectomy (RP) with extended pelvic lymph node dissection (ePLND).
  
  
  METHODS
  The study cohort consisted of 1,282 men with clinically localized PCa who underwent RP and ePLND, including removal of obturator, external iliac, and hypogastric lymph nodes, between 01/2007 and 08/2011. Descriptive measurements included preoperative clinical and biopsy variables, such as prostate-specific antigen (PSA), clinical stage (CS), primary and secondary biopsy Gleason pattern, and percentage of positive cores. We used the area under curve (AUC) of the receiver operator characteristic analysis to quantify accuracy of the model to predict LNI. The extent of over- or under-estimation was explored graphically within loess calibration plots.
  
  
  RESULTS
  The median number of removed lymph nodes was 15 with an interquartile range of 12-20. Twelve percent (n = 155) of men had LNI. Preoperative clinical and biopsy characteristics differed significantly (all P ≤ 0.002) between men with LNI and those without. External validation of the previously reported updated LNI nomogram showed very good accuracy (AUC: 0.829). A nomogram-derived cut-off of 4% could lead to a reduction of 48% of lymph node dissection, while missing 10% of patients with LNI.
  
  
  CONCLUSIONS
  We report the external validation of an updated LNI nomogram, demonstrating accuracy and applicability in a different European cohort. A nomogram-derived cut-off of 4% confirmed good performance characteristics within a different external validation cohort.
authors: Martini Clinic, Prostate Cancer Centre at University Medical Centre Hamburg-Eppendorf, Hamburg, Germany. jenshansen81@gmail.com
authors: Jens
authors: J
authors: Hansen
authors: Michael
authors: M
authors: Rink
authors: Marco
authors: M
authors: Bianchi
authors: Luis A
authors: LA
authors: Kluth
authors: Zhe
authors: Z
authors: Tian
authors: Sascha A
authors: SA
authors: Ahyai
authors: Shahrokh F
authors: SF
authors: Shariat
authors: Alberto
authors: A
authors: Briganti
authors: Thomas
authors: T
authors: Steuber
authors: Margit
authors: M
authors: Fisch
authors: Markus
authors: M
authors: Graefen
authors: Pierre I
authors: PI
authors: Karakiewicz
authors: Felix K-H
authors: FK
authors: Chun
mesh_terms: D000368:Aged; D015331:Cohort Studies; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods* / Q000592:standards*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D010388:Pelvis / Q000473:pathology* / Q000601:surgery; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D012189:Retrospective Studies