Prognostic significance of serum testosterone level in patients with castration-resistant prostate cancer treated with cabazitaxel

Background: Serum testosterone level is a potential prognostic marker for castration-resistant prostate cancer. However, its role as a prognostic marker in cabazitaxel chemotherapy remains unclear. This study aimed to elucidate the clinical significance of serum testosterone levels before cabazitaxel chemotherapy. Methods: This single-institution, retrospective study included 47 patients with metastatic castration-resistant prostate cancer (mCRPC) who received cabazitaxel therapy. Serum testosterone levels were measured before the initiation of cabazitaxel therapy. Results: Progression-free survival and overall survival (OS) were not significantly different between patients with high and low serum testosterone levels. Analysis of patients aged <70 years revealed that those with high serum testosterone levels (total testosterone level > 0.055 ng/mL) had significantly longer OS than those with low serum testosterone levels (total testosterone level < 0.055 ng/mL, p = 0.012). Multivariate analysis revealed that low serum testosterone levels (hazard ratio [HR] = 11.874, 95% confidence interval [CI] 2.076-67.953, p = 0.005) and high prostate-specific antigen levels (HR = 18.051, 95% CI 2.462-132.347, p = 0.004) in the pretreatment phase were independent prognostic factors for OS in patients receiving cabazitaxel therapy. Conclusions: Serum testosterone level may be a prognostic marker for cabazitaxel therapy in patients with mCRPC who are younger than 70 years, and high serum testosterone levels may lead to longer survival.