Login to Access Video or Poster Abstract: MP28-16
Sources of Funding: Grant/research funding from AstraZeneca and Takeda Pharmaceutical Company

Introduction

Previously, we reported that prostatic tissue androgen levels (tissue testosterone / tissue dihydrotestosterone ratio (tissue T/DHT ratio)) in prostate biopsy could predict time to castration-resistant prostate cancer (CRPC) in men with castration-sensitive prostate cancer (Andrology 2013). In this study, we investigated that if tissue T/DHT ratio in prostate biopsy specimens could predict survival for men with mCRPC.

Methods

We identified consecutive 34 patients with mCRPC. All patients had undergone prostate needle biopsy after failed to CRPC. We analyzed prostatic tissue androgen levels using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We analyzed the correlations between prostate cancer-specific survival (PCSS) and clinicopathological characteristics, including baseline prostate-specific antigen (PSA) levels, time to CRPC, previous use of docetaxel, previous use of abiraterone or enzalutamide, and tissue T/DHT ratio. Statistical analyses were assessed using Cox proportional hazards regression models.

Results

The median age was 74 years and the median follow-up duration was 7.4 months. The median baseline PSA value was 20.1 ng/ml and median T/DHT ratio was 1.5. The median time to CRPC was 14 months. The number of previous use of docetaxel and previous use of abiraterone or enzalutamide were 19 (55.9%) and 6 (26.5%), respectively. In multivariate analysis, time to CRPC (time to CRPC<14 months; HR7.1, 95%CI1.63-38.1, p=0.022) and tissue T/DHT ratio (T/DHT ratio>1.5; HR5.2, 95%CI1.1-23.6, p=0.035) were significant risk factors for PCSS.

Conclusions

Time to CRPC and tissue T/DHT ratio were significant risk factors for PCSS. Tissue T/DHT ratio would be helpful in predicting survival and might be valuable for counseling for men with mCRPC.

Funding

Grant/research funding from AstraZeneca and Takeda Pharmaceutical Company