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.
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.
Briganti
Alberto
A
Department of Urology, Vita-Salute University San Raffaele, Milan, Italy. briganti_alberto@yahoo.it
Passoni
Niccolò
N
Ferrari
Matteo
M
Capitanio
Umberto
U
Suardi
Nazareno
N
Gallina
Andrea
A
Da Pozzo
Luigi Filippo
LF
Picchio
Maria
M
Di Girolamo
Valerio
V
Salonia
Andrea
A
Gianolli
Liugi
L
Messa
Cristina
C
Rigatti
Patrizio
P
Montorsi
Francesco
F
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
D019275:Radiopharmaceuticals; D017430:Prostate-Specific Antigen; D013669:Technetium Tc 99m Medronate