Baseline neutrophil-to-lymphocyte ratio predicts the prognosis of castration-resistant prostate cancer treated with abiraterone acetate.

Abiraterone acetate (AA), a CYP17 inhibitor, now has a crucial role in the treatment of castration-resistant prostate cancer (CRPC), and previous studies have reported several prognostic clinical factors for AA treatment. The neutrophil-to-lymphocyte ratio (NLR) has also been investigated for a CRPC treatments in a few reports, however it has not been identified to be a prognostic factor for AA treatment in Japanese patients. The present study aimed to assess the association of the baseline NLR with the overall survival (OS) in CPRC patients treated by AA. The present study retrospectively reviewed a total of 90 consecutive patients with CRPC treated with AA from 2011 to 2016 at Yokohama City University Medical Center and National Cancer Center Hospital East. The primary endpoint of the study was the OS, which was defined as the survival from the start of AA administration. The secondary endpoint was the prostate-specific antigen (PSA) response. PSA response was defined as a reduction in antigen levels of >50%. Complete blood cell counts were performed, and the NLR was calculated using the neutrophil and lymphocyte counts obtained on the same day or a few days prior to the initiation of AA therapy. The NLR cut-off point was determined to be 3.76 for the OS, and divided into the high NLR group of 34 patients and the low NLR group of 56 patients. A PSA response was obtained in 8 patients (23.5%) in the high NLR group and in 24 (42.9%) in the low NLR group. The difference of PSA response between the two groups was significant (P=0.037). Kaplan-Meier curves demonstrated that a high NLR [NLR ≥3.76; median OS: 8.4 months; 95% confidence interval (CI): 6.325-10.475 months] was correlated with a risk of mortality compared with a low NLR (NLR <3.76; median OS not reached). A multivariate analysis demonstrated that the NLR was an independent predictor for the OS (hazard ratio: 2.682; 95% CI: 1.143-6.293; P=0.023). The findings suggest that the NLR may be a useful novel biomarker for predicting the prognosis of CRPC patients treated with AA.