Predicting Early Castration-Resistant Prostate Cancer in Metastatic Prostate Cancer: Development and Internal Validation of a Nomogram for Patients Receiving Abiraterone plus Androgen-Deprivation Therapy

Background Some men with metastatic prostate cancer progress to castration-resistant disease rapidly after initiating abiraterone acetate in combination with androgen-deprivation therapy. Early risk assessment may guide subsequent follow-up and treatment decisions. This study aimed to identify factors associated with progression within two years and to develop a straightforward predictive tool for the early identification of high-risk patients. Methods A retrospective analysis of 208 men with bone-only metastatic prostate cancer who received abiraterone acetate in combination with androgen-deprivation therapy at our single institution between January 2019 and March 2025 was conducted. Univariate and multivariate Cox proportional hazards regression analyses were employed to identify predictors of progression to metastatic castration-resistant prostate cancer (mCRPC). Subsequently, a nomogram was developed based on the multivariate model and internally validated using 1,000 bootstrap resamples. The model's discrimination, calibration, and clinical utility were then assessed. Results Of the 208 patients, 80 (38.5%) progressed to mCRPC within two years. Multivariate analysis identified four independent predictors of early progression: Gleason score of 9–10 (HR = 4.334, 95% CI: 2.248–8.355), clinical T stage 3–4 (HR = 2.315, 95% CI: 1.168–4.589), higher prostate-specific antigen nadir (nPSA; HR = 1.267, 95% CI: 1.119–1.435), and shorter time to nPSA(TTN;HR = 0.863, 95% CI: 0.801–0.930). In Kaplan–Meier analysis, each of these factors was significantly associated with shorter progression-free survival (log-rank P < 0.001). Receiver operating characteristic (ROC) analysis yielded an area under the curve (AUC) of 0.894 (95% CI: 0.851–0.938), indicating the developed nomogram possesses excellent discriminatory capability. The calibration curve demonstrated high concordance between predicted and actual outcomes, with a mean absolute error of 0.018. Decision curve analysis (DCA) further confirmed the model's favorable clinical utility. Conclusion Patients with higher Gleason scores (9–10), advanced clinical T stage (T3–4), higher nPSA, and shorter TTN are at increased risk of early castration resistance following treatment with abiraterone acetate plus androgen deprivation therapy. The developed nomogram serves as a practical tool to estimate individualized two-year progression risk, potentially facilitating tailored clinical management through intensified monitoring and timely treatment modification in high-risk individuals. External validation in prospective, multicenter cohorts is warranted before broader clinical application.