Earlier use of androgen receptor-axis-targeted drugs may improve overall survival in patients with non-metastatic castration-resistant prostate cancer.

BACKGROUND

To evaluate the role of androgen receptor-axis-targeted drugs (ARAT) in non-metastatic castration-resistant prostate cancer (nmCRPC) versus mCRPC.

METHODS

Chemotherapy-naive patients (n = 114) with CRPC who had no metastasis at the time of diagnosis were included in this retrospective study. All patients were treated with ARAT at Jikei University and its affiliated hospitals from July 2014 to March 2017. The patients were stratified into nmCRPC (n = 81) and mCRPC (n = 33) groups according to their metastatic status at ARAT induction. The primary outcome measure was difference in overall survival (OS) between groups from the time of CRPC diagnosis. The patients were compared for progression-free survival (PFS) and prostate-specific antigen (PSA) response. The predictors of OS were explored by a multivariate Cox model.

RESULTS

The baseline demographics did not differ significantly between the groups. The median observation period from the diagnosis of CRPC was 24.5 months (range: 3-135) and 20 months (range: 1-66) in nmCRPC and mCRPC groups, respectively. The nmCRPC group demonstrated better OS from the time of diagnosis of CRPC in Kaplan-Meier analysis than mCRPC group (86 months vs 40 months; P = 0.004), with similar results obtained for PFS (P = 0.048) and PSA response (P = 0.0014). Multivariate analysis demonstrated non-metastatic status, low PSA, and long PSA doubling time (PSADT) at ARAT induction as the significant predictors of longer OS (P = 0.044, 0.0001, and 0.026, respectively).

CONCLUSIONS

Early use of ARAT may improve OS, PFS, and PSA response in CRPC. Larger, prospective studies will be required to confirm our findings.