Clinical utility of IDC-P (intraductal carcinoma of the prostate) in the decision making of initial treatment for metastatic hormone-sensitive prostate cancer.

Abstract

93 Background: In recent years, the usefulness of using androgen receptor axis-targeted agents (ARAT) such as abiraterone, enzalutamide, and apalutamide for metastatic hormone-sensitive prostate cancer (mHSPC) in the up-front setting has been demonstrated. However, it is still unclear which patients could truly benefit from these treatments. On the other hand, intraductal carcinoma of prostate (IDC-P) is a known poor prognostic factor for prostate cancer patients. In the present study, we investigated the association between the presence of IDC-P and therapeutic response to mHSPC. Methods: This retrospective analysis included 318 patients with mHSPC from thirteen affiliated institutions between 2014 and 2021, and evaluated biopsy specimens for the presence of IDC-P. All patients were grouped by their first-line treatment, either 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). We compared 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 response to each treatment. The PFS2 was defined as the period from diagnosis of mHSPC to disease progression on second-line therapy or death. Propensity score matching was used for one-to-one nearest neighbor matching in order to minimize the potential effects of selection bias and confounding factors. The clinicopathological variables of 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, OS and PFS2 of IDC-P positive cases were significantly prolonged in the ARAT group compared to the conventional group (OS: hazard ratio [HR], 0.36; p=0.047; PFS2: HR, 0.30; p<0.001). In contrast, IDC-P negative cases did not show a difference in OS and PFS2 between the ARAT and the conventional groups (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 may be a reliable indicator to implement ARAT as first-line therapy.