Impact of treatment modality on overall survival (OS) in localized ductal prostate adenocarcinoma (PCa): A national cancer database (NCDB) analysis

Introduction & Objectives: Ductal adenocarcinoma is considered a rare histological variant of PCa. Given the rarity of this subtype, optimal treatment strategies for men with nonmetastatic ductal PCa is largely unknown. We aimed to describe the impact of surgery, radiotherapy, and systemic therapy on OS in men with nonmetastatic ductal PCa. Materials & Methods: We retrospectively selected 2209 cases of ductal PCa, diagnosed between 2004 and 2015, within the NCDB. Exclusion of metastatic patients yielded a total sample of 1993 individuals. Cox regression analysis tested the impact of treatment (surgery, radiotherapy, systemic therapy and no treatment) on OS. Covariates included age, race, Charlson comorbidity score (CCI), clinical T stage, biopsy Gleason score, serum prostate specific antigen (PSA), and income. Adjusted Kaplan-Meier estimates were used to visualize the impact of treatment modality on OS. Results: In men with nonmetastatic ductal PCa, median (IQR) age and PSA were 67 (61-74) years and 6.3 (4.3-10.8) ng/mL, respectively. Further, 9.8% (n=195) of patients presented with cT3 disease or higher, 3.4% (n=68) presented a CCI score ≥4, and 40.6% (808) presented with a Gleason biopsy score ≥4. Further, 1212 (60.8%) patients were treated surgically, 406 (20.4%) with radiotherapy, 102 (5.1%) with systemic therapies, and 273 (13.7%) received no treatment. Multivariable analysis revealed that in comparison to men treated surgically, OS was significantly lower for patients receiving radiotherapy (HR 2.6; 95% CI 1.7-4.0) and systemic therapies (HR 9.1; 95% CI 5.0-16.5). Adjusted Kaplan-Meier curves are shown in Figure 1. Figure 1. Kaplan-Meier OS estimates of 1993 nonmetastatic ductal PCa patients, diagnosed between 2004 and 2015, within the NCDB, stratified by treatment. Conclusions: Our findings show that in the rare ductal PCa variant, starting treatment with surgery offers more favorable long-term OS outcomes when compared to radiotherapy and systemic therapies. While residual selection bias might persist after adjustment, the rarity of this specific malignancy precludes the possibility of a future trial, and the presented data represents the best available level of evidence on this topic