Validation of a bone scan positivity risk table in non‐metastatic castration‐resistant prostate cancer

• Published in: BJU international 2016-10, Vol.118 (4), p.570-577
• Main Authors: Freedland, Stephen J., Howard, Lauren E., Hanyok, Brian T., Kadiyala, Vishnu K., Kuang, Jameson Y., Whitney, Colette A., Wilks, Floyd R., Kane, Christopher J., Terris, Martha K., Amling, Christopher L., Cooperberg, Matthew R., Aronson, William J., Moreira, Daniel M.
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Bone Neoplasms - diagnostic imaging; Bone Neoplasms - epidemiology; Bone Neoplasms - secondary; Confidence intervals; Humans; Male; Metastasis; Prostate cancer; prostate‐specific antigen; Prostatic Neoplasms, Castration-Resistant - pathology; Radionuclide Imaging; Retrospective Studies; Risk Assessment; validation studies
• ISSN: 1464-4096; 1464-410X
• DOI: 10.1111/bju.13405

Objectives To test the external validity of a previously developed risk table, designed to predict the probability of a positive bone scan among men with non‐metastatic (M0) castration‐resistant prostate cancer (CRPC), in a separate cohort. Patients and Methods We retrospectively analysed 429 bone scans of 281 patients with CRPC, with no known previous metastases, 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 previous 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 prostate‐specific antigen (PSA): hazard ratio (HR) 2.13; 95% confidence interval (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 men with a PSA level