Purpose: Bone scan index (BSI) is an objective tool for quantifying bone metastasis load. We assessed its prognostic usefulness in patients with metastatic castration-resistant prostate cancer (CRPC) treated with enzalutamide (ENZ) or abiraterone acetate (AA).
Materials and methods: We analyzed 40 patients who received ENZ or AA treatment (ENZ/AA) for metastatic CRPC. The Cox proportional hazards model and a C-index were used to investigate associations between overall survival (OS) and BSI, and patient age, prostate-specific antigen, time to CRPC, previous docetaxel use, and pain.
Results: Median OS after ENZ/AA was 17.8 months. All patient deaths (n = 19; 47.5%) were from prostate cancer. In multivariate analysis, decreased BSI was an independent predictor for longer OS (hazard ratio, 8.97; P = .011). Inclusion of BSI improved the C-index from 0.721 to 0.792 in predicting OS after ENZ/AA.
Conclusions: Decreased BSI after ENZ/AA independently predicts longer OS.
Keywords: Androgen receptor; Biomarkers; Independent; Prostatic neoplasms; Radionuclide imaging.
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