Alkaline phosphatase (ALP) value at diagnosis of CRPC and response to primary androgen deprivation therapy may predict metastasis in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC).

294 Background: Numerous therapeutic options are available for metastatic castration-resistant prostate cancer (mCRPC). However, current therapeutic options remain inadequate for non-metastatic CRPC (nmCRPC); furthermore, there is a paucity of clear evidence to show who may be targeted for aggressive therapy among nmCRPC patients. Therefore, the objective of this retrospective study was to explore predictors of metastasis in patients with nmCRPC and to identify a subpopulation of nmCRPC patients who may benefit from aggressive therapy. Methods: A total of 115 patients with CRPC who had no metastasis at the time of diagnosis of CRPC were included in this retrospective study. All patients were treated at Jikei University Hospital. The primary outcome measure was metastasis-free survival (MFS) from the time of diagnosis of CRPC. Predictors of MFS were also explored with a multivariate Cox model. Results: The median observation period after diagnosis of CRPC in these patients was 30 months. Kaplan-Meier analysis revealed a median MFS of 76 months in these patients. Multivariate analysis demonstrated that low ALP values at diagnosis of CRPC and favorable response to primary androgen deprivation therapy (ADT) were significant predictors of longer MFS ( P = 0.011, and 0.031, respectively). Conclusions: Study results suggest that high ALP values at diagnosis of CRPC and poor response to primary ADT may predict metastasis in patients with nmCRPC. Further prospective studies will be required in more patients to confirm our findings. Univariate/multivariate analysis of factors contributing to MFS in nmCRPC patients. [Table: see text]