Unveiling the pathologic predictor in patients with metastatic hormone-sensitive prostate cancer treated with abiraterone: Intraductal carcinoma of the prostate and its subtypes.

e17077 Background: Intraductal carcinoma of the prostate (IDC-P) is a distinct pathological type of prostate cancer (PCa). Its association with poor prognosis in patients has gained widespread recognition. In this study, we aimed to assess whether metastatic hormone-sensitive prostate cancer (mHSPC) patients with different IDC-P statuses and subtypes exhibited varying responses to abiraterone treatment, with the goal of exploring its potential as a predictive pathological marker. Methods: We conducted a retrospective analysis of data from 165 mHSPC patients who received abiraterone treatment. Propensity score matching (PSM) was employed to minimize the potential impact of selection bias and confounding factors. We evaluated PSA response, PSA progression-free survival (PSA-PFS), radiographic progression-free survival (rPFS), and overall survival (OS) based on IDC-P status and its subtypes (pattern 1: loose cribriform or micropapillary; pattern 2: solid or dense cribriform). We also conducted subgroup analyses to explore their predictive value in different patient populations. Results: Following PSM, a cohort of 108 mHSPC patients was established, among whom IDC-P was confirmed in 54 out of 108 (50%) individuals. Of these, 12/54 (22.2%) exhibited IDC-P pattern 1, while 42/54 (77.8%) had IDC-P pattern 2. The median follow-up duration for the entire cohort was 32.5 months, with median PSA-PFS, rPFS, and OS values of 24.3 months, 31.9 months, and not reached, respectively. No statistically significant difference was observed in PSA responses among patients with different IDC-P statuses. However, patients with IDC-P demonstrated poorer survival outcomes (PSA-PFS: 18.6 vs. NR months, p = 0.002; rPFS: 23.6 vs. NR months, p = 0.020). Patients with IDC-P pattern 1 exhibited clinical outcomes similar to those without IDC-P, whereas patients with IDC-P pattern 2 had significantly worse prognosis compared to those without IDC-P (PSA-PFS: 18.6 vs. NR months, p = 0.002; rPFS: 22.4 vs. NR months, p = 0.010). Subgroup analyses revealed a significant association between IDC-P pattern 2 and poorer prognosis across most population subgroups. Conclusions: Our study assessed the predictive value of IDC-P and its subtypes in prostate biopsy specimens of mHSPC patients undergoing abiraterone treatment. IDC-P, particularly IDC-P pattern 2, serves as an adverse prognostic indicator in these patients. Therefore, routine reporting of IDC-P and its pattern is important for treatment strategy making for prostate cancer patients.