LAUSR

150 Background: This study aimed to investigate the efficacy of docetaxel and androgen receptor axis-targeted (ARAT) agents in castration-resistant prostate cancer (CRPC) patients with intraductal carcinoma of the prostate (IDC-P). Methods: We retrospectively identified 311 CRPC patients from June 2002 to February 2016. All patients were initially administered with androgen deprivation therapy (ADT), followed by docetaxel or ARAT (abiraterone or enzalutamide) after progressing to CRPC. The primary outcome of interest was overall survival (OS) from the time of CRPC diagnosis and progression-free survival (PFS) from the time of administration of docetaxel or ARAT. Results: IDC-P was found in 180 of 311 patients. The median OS was 33.4 and 64.0 months with and without IDC-P, respectively (hazards ratio [HR], 2.14; P < 0.001). For the first treatment for CRPC, docetaxel was administered to 71 and 50 patients with and without IDC-P, respectively, with a median OS of 30.4 and 64.0 months, respectively (HR, 2.62; P < 0.001). ARAT was administered to 109 and 81 patients with and without IDC-P, respectively, with a median OS of 45.0 and 69.9 months, respectively (HR, 1.84; P = 0.017). Regarding patients with IDC-P, the OS in patients who were administered with ARAT was longer than that in those administered with docetaxel (HR, 0.58; P = 0.008). The median PFS was 7.5 and 12.1 months with and without IDC-P, respectively (HR, 1.36; P = 0.03). Multivariate analysis showed that the prognostic factors for OS were the presence of IDC-P (HR, 1.91; P < 0.001), and administration of ARAT (HR, 0.66; P = 0.02). Conclusions: The presence of IDC-P is an independent prognostic factor for OS and PFS in CRPC patients. ARAT may prolong OS in CRPC patients with IDC-P.