Prognostic Significance of the Proportion of Ductal Component in Ductal Adenocarcinoma of the Prostate

Purpose In prostate cancer ductal adenocarcinoma is mixed with the usual acinar adenocarcinoma. However, to our knowledge whether the proportion of the ductal component affects oncologic outcomes is currently unknown. We investigated whether the proportion of the ductal component predicts oncologic outcomes in ductal adenocarcinoma. Materials and Methods We retrospectively reviewed clinical data on 3,038 patients with prostate cancer who underwent radical prostatectomy at our institution between 2005 and 2014. We excluded patients who received neoadjuvant or adjuvant treatment. Patients were stratified based on the proportion of the ductal component. We compared the probability of biochemical recurrence between groups and investigated how the proportion of the ductal component influences biochemical recurrence using Kaplan-Meier estimates and Cox regression models, respectively. Results Of 2,648 patients 101 (3.8%) had ductal adenocarcinoma and 2,547 (96.2%) had acinar adenocarcinoma. Freedom from biochemical recurrence in patients with ductal adenocarcinoma was significantly lower than in those with acinar adenocarcinoma (p <0.001). When ductal cases were stratified by the proportion of the ductal component, freedom from biochemical recurrence in the high ductal component group was significantly lower compared to that in the low ductal component group (30% or greater vs less than 30%, p = 0.023). On univariate and multivariate Cox regression analyses, a high ductal component was a significant predictor of biochemical recurrence (p <0.001). Conclusions The prognosis for ductal adenocarcinoma can be stratified by the proportion of the ductal component. This marker could potentially be used as a surrogate for poor prognosis or as a determinant for adjuvant therapy.