The Prognostic Value of the Proportion and Architectural Patterns of Intraductal Carcinoma of the Prostate in Patients with De Novo Metastatic Prostate Cancer

PURPOSE: Intraductal carcinoma of the prostate is an adverse prognosticator of prostate cancer. However, the roles of proportion and architectural patterns of intraductal prostate carcinoma in patient outcomes remain unclear. MATERIALS AND METHODS: We retrospectively analyzed data on 644 patients with de novo metastatic prostate cancer between 2010 and 2017. Intraductal carcinoma of the prostate was identified from 12-core prostate biopsy. We calculated the proportion of intraductal prostate carcinoma and identified patterns according to the 2016 WHO classification. Propensity score matching was performed to balance baseline characteristics between patients with and without intraductal prostate carcinoma. Kaplan-Meier curves and Cox regression were used for survival analyses. The end points were castration resistant prostate cancer-free survival and overall survival. RESULTS: Of the 644 patients 180 (28.0%) harbored intraductal carcinoma of the prostate. A 10% or greater incidence of the carcinoma was independently associated with worse prognosis (castration resistant prostate cancer-free survival HR 2.06, 95% CI 1.51-2.81, p <0.001, and overall survival HR 2.52, 95% CI 1.52-4.16, p <0.001), as was pattern 2 intraductal carcinoma of the prostate (HR 1.86, 95% CI 1.40-2.49, p <0.001, and HR 2.12, 95% CI 1.29-3.46, p = 0.003, respectively). Based on these 2 risk factors all men were classified into 5 groups. Patients in group 0 (no intraductal carcinoma of the prostate) and prostate intraductal carcinoma group 1 (less than 10% intraductal carcinoma, pattern 1) had favorable median castration resistant prostate cancer-free survival (18.0 vs 16.9 months, p = 0.871) and median overall survival (neither reached, p = 0.698). Men in intraductal carcinoma of the prostate group 4 (10% or greater intraductal carcinoma, pattern 2) harbored the worst outcomes (median castration resistant prostate cancer-free and overall survival 8.4 and 29.9 months, respectively). Group 2 (less than 10% intraductal carcinoma, pattern 2, with median castration resistant prostate cancer-free and overall survival 14.2 and 45.9 months) and group 3 (10% or less prostate intraductal carcinoma, pattern 1, with median castration resistant prostate cancer-free and overall survival 11.9 and 39.7 months, respectively) had an intermediate prognosis. CONCLUSIONS: A 10% or greater proportion of intraductal carcinoma of the prostate and pattern 2 were 2 unfavorable prognosticators of metastatic prostate cancer. Pathological reporting criteria based on intraductal carcinoma of the prostate could improve the prediction of patient outcomes and optimize treatment decisions.