Predictive factors of survival outcomes in first‐line therapy for metastatic castration‐resistant prostate cancer.

Objectives: To investigate predictive factors of survival of metastatic castration‐resistant prostate cancer patients undergoing first‐line treatment with androgen receptor pathway inhibitors or docetaxel. Methods: Japanese patients with metastatic castration‐resistant prostate cancer treated with androgen receptor pathway inhibitor or docetaxel between 2008 and 2018 were included. The differential impact of various clinicopathological factors on the outcome, including progression‐free survival and overall survival, was compared between treatment with androgen receptor pathway inhibitor and docetaxel. Results: Of 254 patients with metastatic castration‐resistant prostate cancer, 119 (46.9%) and 135 (53.2%) were treated with androgen receptor pathway inhibitor and docetaxel, respectively. The multivariate analysis showed that androgen receptor pathway inhibitor was an independent prognostic factor for better progression‐free survival (hazard ratio 0.62, 95% confidence interval 0.42–0.92, P = 0.016) and overall survival (hazard ratio 0.61, 95% confidence interval 0.41–0.93, P = 0.021), compared with docetaxel. Pretreatment prostate‐specific antigen levels and time to castration‐resistant prostate cancer were differentially associated with progression‐free survival and overall survival between androgen receptor pathway inhibitor or docetaxel. In patients who presented <6 months to castration‐resistant prostate cancer, progression‐free survival was shorter in those treated with androgen receptor pathway inhibitor (median 1.1 months, 95% confidence interval 0.2–2.8 months) compared with those who received docetaxel (median 5.0 months, 95% confidence interval 1.8–6.7 months; P = 0.014). Conclusions: First‐line therapy with androgen receptor pathway inhibitor is associated with a better prognosis when compared with docetaxel, even after adjustment for prognostic factors. However, a shorter time to castration‐resistant prostate cancer is associated with better progression‐free survival for patients receiving docetaxel, suggesting that docetaxel is the preferred option for patients with a shorter time to castration‐resistant prostate cancer. [ABSTRACT FROM AUTHOR]