Validation of a bone scan positivity risk table in non-metastatic castration-resistant XXXX .

@entity1 @entity263 @entity3
OBJECTIVES: We have previously developed a risk table to predict the probability of a positive bone scan among @entity1 with non-metastatic castrate resistant @entity263 (M0 CRPC). Herein, we tested its external validity of this risk table in a separate cohort. @entity1 AND METHODS: We retrospectively analyzed 429 bone scans of 281 CRPC @entity1 with no known prior @entity3 treated at three Veterans Affairs Medical Centers. We assessed the predictors of a positive scan using generalized estimating equations. Area under the curve (AUC), calibration plots and decision curve analysis were used to assess the performance of our prior model to predict a positive scan in the current data. RESULTS: A total of 113 scans (26%) were positive. On multivariable analysis, the only significant predictors of a positive scan were log-transformed PSA (HR 2.13, 95%CI 1.71-2.66, p<0.001) and log-transformed PSA doubling time (PSADT; HR=0.53, 95%CI 0.41-0.68, p<0.001). Among @entity1 with a PSA <5 ng/ml, the rate of positive scans was 5%. The previously developed risk table had an AUC of 0.735 to predict positive bone scan with excellent calibration and provided additional net benefit in the decision curve analysis. CONCLUSIONS: We have validated our previously developed table to predict the risk of a positive bone scan among @entity1 with M0/Mx CRPC. Use of this risk table may allow better tailoring of @entity1 ' scanning to identify @entity3 early while minimizing over-imaging. Regardless of PSADT, positive bone scans were rare in @entity1 with a PSA <5 ng/ml. This article is protected by copyright. All rights reserved.
