Comparison of Survival Outcomes and Risk Factors Between Ductal Carcinoma of the Prostate and Acinar Adenocarcinoma of the Prostate: A Population-based Propensity Score–matching Study

BACKGROUND: Ductal carcinoma of the prostate (DCP) is a rare type of prostate cancer (PCa) with a higher degree of infiltration and worse prognosis than acinar adenocarcinoma of the prostate (ACP). Previous reports comparing DCP and ACP have not been very reliable and involved small sample sizes. OBJECTIVE: To assess differences in mortality between ACP and DCP in a large-scale study. DESIGN, SETTING, AND PARTICIPANTS: Data were downloaded from the Surveillance, Epidemiology, and End Results database in June 2022. Data for 823 939 patients diagnosed with PCa from 2004 to 2019 were examined, excluding cases with survival data missing or pathological types other than DCP and ACP. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Prognostic and risk factors for DCP were analyzed by generating a propensity score–matched cohort of DCP and ACP cases (1:5). Adjusted Cox models were constructed to determine hazard ratios (HRs) with 95% confidence intervals (CIs) for cancer-specific mortality (CSM) and overall mortality (OM) RESULTS AND LIMITATIONS: A total of 822 607 cases (99.8%) has ACP and 1332 (0.2%) had DCP. In comparison to ACP, age at diagnosis was significantly lower for DCP (≤66 yr: 38.0% vs 50.7%; p < 0.001) and a higher proportion of DCP patients distant metastases (13.7% vs 5.1%; p < 0.001). In comparison to the ACP group, significantly higher proportions of the DCP group underwent surgery (66.1% vs 38.1%; p < 0.001), radiotherapy (13.7% vs 3.1%; p < 0.001), or systemic therapy (18.2% vs 3.3%; p < 0.001). However, the median overall survival time was significantly shorter for DCP patients (44.0 vs 73.0 mo; p < 0.001). DCP patients also had higher risk of CSM (HR 2.07, 95% CI 1.68–2.56; p < 0.001) and OM (HR 2.73 95% CI 2.42–3.08; p < 0.001) after propensity score matching to adjust for the influence of baseline variables. Subgroup analysis showed that DCP patients who had surgical treatment had better CSM than those without surgery, while DCP patients with regional and lower stage had better OM than those with distant stage (both p < 0.05 for interaction). CONCLUSIONS: The risk of CSM and OM is significantly higher for DCP than for ACP. Earlier detection (lower stage) and surgical treatment are beneficial factors for DCP prognosis. PATIENT SUMMARY: We studied survival rates for two different types of prostate cancer. We found that survival is worse for the rarer ductal carcinoma of the prostate (DCP) than for the more common acinar adenocarcinoma of the prostate. Both early diagnosis when the cancer is at a lower stage and surgical treatment are beneficial for survival in patients with DCP.