Clinical utility of intraductal carcinoma of the prostate in treatment selection for metastatic hormone‐sensitive prostate cancer

Abstract Background In recent years, the usefulness of androgen receptor axis‐targeted agents (ARATs) such as abiraterone, enzalutamide, and apalutamide for the upfront treatment of metastatic hormone‐sensitive prostate cancer (mHSPC) has been demonstrated. However, it remains unclear which patients would truly benefit from these treatments. Furthermore, intraductal carcinoma of the prostate (IDC‐P) is a known poor prognostic factor in patients with prostate cancer. We investigated the association between the presence of IDC‐P and response to therapy in patients with mHSPC. Methods This retrospective analysis included 318 patients with mHSPC who received treatment at Nagoya University and its 12 affiliated institutions between 2014 and 2021. Their biopsy specimens were evaluated for the presence of IDC‐P. The patients were classified according to their first‐line treatment into the ARAT ( n = 100, receiving a combination of androgen‐deprivation therapy [ADT] and ARAT) or conventional therapy ( n = 218, receiving ADT with or without standard antiandrogen agents) group. We compared the overall survival (OS) and second progression‐free survival (PFS2) between the ARAT and conventional groups according to the presence of IDC‐P to evaluate whether presence of IDC‐P predicts the response to each treatment. PFS2 was defined as the period from mHSPC diagnosis to disease progression on second‐line treatment or death. Propensity score matching with one‐to‐one nearest‐neighbor matching was used to minimize the potential effects of selection bias and confounding factors. The clinicopathological variables of the patients were well‐balanced after propensity score matching. Results Most patients in the ARAT (79%) and conventional therapy (71%) groups were ICD‐P positive. In the propensity score‐matched cohort, the OS and PFS2 of IDC‐P‐positive patients were significantly longer in the ARAT group than in the conventional group (OS: hazard ratio [HR], 0.36; p = 0.047; PFS2: HR, 0.30; p < 0.001). In contrast, no difference in OS and PFS2 was observed between the ARAT and conventional groups in IDC‐P‐negative patients (OS: HR, 1.09; p = 0.920; PFS2: HR, 0.40; p = 0.264). Conclusions The findings highlight a high prevalence of IDC‐P among patients with mHSPC and suggest that IDC‐P positivity may be a reliable indicator that ARAT should be implemented as first‐line treatment.