title: When to perform bone scan in patients with newly diagnosed prostate cancer: external validation of the currently available guidelines and proposal of a novel risk stratification tool.
abstract: BACKGROUND
  Several guidelines have indicated that in patients with well-differentiated or moderately well-differentiated prostate cancer (PCa), a staging bone scan may be omitted. However, the guidelines recommendations have not yet been externally validated.
  
  
  OBJECTIVE
  The aim of the study was to externally validate the available guidelines regarding the need for a staging bone scan in patients with newly diagnosed PCa. Moreover, we developed a novel risk stratification tool aimed at improving the accuracy of these guidelines.
  
  
  METHODS
  The study included 853 consecutive patients diagnosed with PCa between January 2003 and June 2008 at a single centre. All patients underwent bone scan using technetium Tc 99m methylene diphosphonate at diagnosis.
  
  
  METHODS
  The area under the curve (AUC) of the criteria suggested by the guidelines (European Association of Urology, American Urological Association, National Comprehensive Cancer Network, and American Joint Committee on Cancer) to perform a baseline bone scan was assessed and compared with the accuracy of a classification and regression tree (CART) including prostate-specific antigen (PSA), clinical stage, and biopsy Gleason sum as covariates.
  
  
  CONCLUSIONS
  The AUC of the guidelines ranged between 79.7% and 82.6%. However, the novel CART model, which stratified patients into low risk (biopsy Gleason ≤7, cT1-T3, and PSA <10 ng/ml), intermediate risk (biopsy Gleason ≤7, cT2/T3, and PSA >10 ng/ml), and high risk (biopsy Gleason >7) was significantly more accurate (AUC: 88.0%) than all the guidelines (all p≤0.002). The limitation of this study resides in its retrospective design. Moreover, the proposed risk stratification tool can be considered only for patients who are candidates for radical prostatectomy until validated in other clinical settings.
  
  
  CONCLUSIONS
  This is the first study aimed at externally validating the available guidelines addressing the need for staging baseline bone scans in PCa patients. All guidelines showed high accuracy. However, their accuracy was significantly lower compared with the accuracy of the novel risk stratification tool. According to this tool, staging bone scans might be considered only for patients with a biopsy Gleason score >7 or with a PSA >10 ng/ml and palpable disease (cT2/T3) prior to treatment. However, before recommending its use in clinical practice, our model needs to be externally validated.
authors.affiliation: Department of Urology, Vita-Salute University San Raffaele, Milan, Italy. briganti_alberto@yahoo.it
authors.forename: Alberto
authors.initials: A
authors.lastname: Briganti
authors.forename: Niccolò
authors.initials: N
authors.lastname: Passoni
authors.forename: Matteo
authors.initials: M
authors.lastname: Ferrari
authors.forename: Umberto
authors.initials: U
authors.lastname: Capitanio
authors.forename: Nazareno
authors.initials: N
authors.lastname: Suardi
authors.forename: Andrea
authors.initials: A
authors.lastname: Gallina
authors.forename: Luigi Filippo
authors.initials: LF
authors.lastname: Da Pozzo
authors.forename: Maria
authors.initials: M
authors.lastname: Picchio
authors.forename: Valerio
authors.initials: V
authors.lastname: Di Girolamo
authors.forename: Andrea
authors.initials: A
authors.lastname: Salonia
authors.forename: Liugi
authors.initials: L
authors.lastname: Gianolli
authors.forename: Cristina
authors.initials: C
authors.lastname: Messa
authors.forename: Patrizio
authors.initials: P
authors.lastname: Rigatti
authors.forename: Francesco
authors.initials: F
authors.lastname: Montorsi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D019540:Area Under Curve; D001706:Biopsy; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary* / Q000601:surgery; D003661:Decision Support Techniques; D006801:Humans; D007558:Italy; D016018:Least-Squares Analysis; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016017:Odds Ratio; D018579:Patient Selection; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013669:Technetium Tc 99m Medronate; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D017430:Prostate-Specific Antigen; D013669:Technetium Tc 99m Medronate