Propensity score‐matched comparison of docetaxel and androgen receptor axis‐targeted agents in patients with castration‐resistant intraductal carcinoma of the prostate

Objective To evaluate the efficacy of docetaxel and androgen receptor axis‐targeted (ARAT) agents in patients with castration‐resistant prostate cancer (CRPC) with intraductal carcinoma of the prostate (IDC‐P) using a propensity score‐matched analysis. Patients and Methods We retrospectively identified 309 patients with CRPC from February 2007 to February 2016 at Nagoya University and its affiliated hospitals. All patients received initial androgen‐deprivation therapy (ADT). After progression to CRPC, they received docetaxel or ARAT (abiraterone or enzalutamide) as first‐line life‐prolonging therapy. Docetaxel (70–75 mg/m2) every 3 weeks vs enzalutamide (160 mg) once daily orally or abiraterone (1 g) once daily plus prednisone (5 mg) twice daily orally was administered. The primary outcome of interest was overall survival (OS) from the time of CRPC diagnosis. A propensity score analysis with a 1:1 ratio using an optimal matching algorithm was used to adjust for confounding factors. Results Overall, 234 patients were analysed. Propensity score‐matching identified 85 patients in each group. There were no significant differences in patient characteristics between the groups. The median OS in the docetaxel group was 38.2 vs 58.3 months in the ARAT group (P = 0.03). For patients with IDC‐P, OS was significantly longer in the ARAT group than the docetaxel group (P = 0.01), and there was no significant difference in each group, as in patients without IDC‐P (P = 0.67). A multivariate analysis showed that the presence of IDC‐P, duration of primary ADT, visceral metastasis, and administration of ARAT as the first‐line treatment for CRPC were independent prognostic factors for OS. Conclusion Administration of ARAT as the first‐line treatment for CRPC may prolong OS more than that of docetaxel, especially in patients with IDC‐P.