The prognostic impact of serum testosterone during androgen-deprivation therapy in patients with metastatic prostate cancer and the SRD5A2 polymorphism

Background: Although testosterone suppression during androgen-deprivation therapy (ADT) and obesity have been reported to affect ADT efficacy, there are few comprehensive analyses on the impact on ADT outcome. Recently, we demonstrated that the SRD5A2 polymorphism was associated with metastatic prostate cancer prognosis. Therefore, in this study, we investigated the relationship between ADT serum testosterone levels or body mass index (BMI) and the prognosis among men treated with primary ADT for metastatic prostate cancer. In addition, we examined the association of serum testosterone levels during ADT with the SRD5A2 polymorphism. Methods: This study included 96 Japanese patients with metastatic prostate cancer. The relationship between clinicopathological parameters, including serum testosterone levels during ADT and BMI, and progression-free survival, overall survival and survival from progression following primary ADT treatment for metastatic prostate cancer was examined. Additionally, the association between the SRD5A2 gene polymorphism (rs523349) and serum testosterone levels during ADT was examined in 86 cases. Results: Among clinicopathological parameters, the lowest quartile of serum testosterone levels during ADT was a significant predictor of better overall survival as well as survival from castration resistance. However, BMI was not associated with prognosis. The CC allele in the SRD5A2 gene (rs523349), encoding the less active 5α-reductase, was associated with lower serum testosterone levels during ADT. Conclusions: Taken together, these findings revealed a dramatic suppression of serum testosterone by ADT was associated with better survival among men with metastatic prostate cancer that have undergone primary ADT, which may be affected by the SRD5A2 gene polymorphism.