LAUSR

The clinical significance of intraductal carcinoma of the prostate (IDC‐P) in men with nonmetastatic prostate cancer (PCa) treated with high‐dose external‐beam radiation therapy remains unclear. The aim of this study was to evaluate the impact of IDC‐P in men who received intensity‐modulated radiation therapy (IMRT) for nonmetastatic PCa. All patients with high‐risk (H‐R) and very high–risk (VH‐R) PCa who received IMRT between September 2000 and December 2013 at our institution were analyzed retrospectively. We re‐reviewed biopsy cores for the presence of IDC‐P. Treatment consisted of IMRT (median: 78 Gy at 2 Gy per fraction) plus 6‐month neoadjuvant hormonal therapy (HT). In total, 154 consecutive patients with H‐R and VH‐R PCa were analyzed. Intraductal carcinoma of the prostate was present in 27.9% (n = 43). The median follow‐up period was 8.4 years. The 10‐year PCa‐specific survival, biochemical failure (BF), clinical failure, and castration‐resistant PCa rates were 90.0%, 47.8%, 27.5%, and 24.5% in patients with IDC‐P, and 96.6%, 32.6%, 10.8%, and 7.0% in those without IDC‐P, respectively (p = 0.12, 0.04, 0.0031, and 0.012, respectively). In multivariable analysis, IDC‐P was not identified as an independent predictive factor for BF (p = 0.26). The presence of IDC‐P was correlated with a significantly higher incidence of disease progression in men with H‐R and VH‐R PCa who received IMRT, although it was not identified as an independent predictive factor for BF. Further investigations are needed to determine the significance of IDC‐P as an independent predictive factor for survival outcomes.