Contemporary analysis of the prognostic significance of intraductal carcinoma of the prostate (IDC-P).

126 Background: IDC-P has become increasingly recognized for its poor prognosis among histologic subtypes. While prior studies have linked IDC-P with higher grade and advanced stage, population-level data remain limited. We utilized the National Cancer Database (NCDB) to identify national treatment patterns and evaluate the overall survival (OS) of IDC-P compared with acinar adenocarcinoma. Methods: The NCDB was queried from 2004 to 2021 for PCa patients with adenocarcinoma or IDC-P. Patient and tumor characteristics and treatment utilization were compared. Temporal trends in IDC-P were analyzed. OS was compared with Kaplan-Meier (KM) method, log-rank, and Cox Proportional Hazards model, adjusting for demographics, stage, comorbidities, Gleason Group, and treatment. Results: Of 2,107,942 PCa patients, 4,242 (0.2%) had IDC-P histology. IDC-P diagnoses increased over time (OR 1.06 per year, p<0.001), particularly after WHO recognition in 2016 (47.9% vs 36.8%, p<0.001). IDC-P patients had higher utilization of radical prostatectomy (RP) (69.5% vs 47.2%), pelvic lymph node dissection (50.2% vs 30.7%), androgen deprivation therapy (ADT) (35.7% vs 25.0%), and chemotherapy (3.4% vs 1.2%) (all p<0.001). Adjuvant (5.9% vs 3.0%) and salvage radiotherapy (3.3% vs 1.6%), serving as surrogate markers of biochemical recurrence, were also more common (p<0.001) as defined by < and ≥6 months post-RP, respectively. IDC-P patients had worse OS overall (14.1 vs 16.5 years, p<0.001), though the difference was attenuated in localized disease (cT1–4N0M0; 16.3 vs 16.7 years, p<0.001). After adjustment for comorbidities, stage, grade, and treatment, IDC-P was not independently associated with higher mortality. Conclusions: Our population-level analysis confirmed that IDC-P is associated with a more aggressive clinical phenotype. Despite this, we found that oncologic outcomes did not differ once disease severity and treatment were accounted for. Guideline-concordant management remains appropriate, though the rising detection of IDC-P and its biologic underpinnings merit ongoing investigation. Multivariable Cox proportional hazards model. Variable (Reference) aHR (95%CI) p-value Age (cont.) 1.048 (1.042-1.053) <0.001 Histo (Ref = Adenocarcinoma) Intraductal Carcinoma 1.138 (0.638-1.967) 0.644 Gleason Group (Ref = 1) 2 3 4 5 1.088 (0.883-1.341)1.290 (1.045-1.594)1.533 (1.239-1.897)2.081 (1.690-2.563) 0.4300.018<0.001<0.001 cT (Ref = 0-1) 2+ 1.458 (1.332-1.596) <0.001 cN (Ref = 0) 1+ 1.272 (1.149-1.408) <0.001 cM (Ref = 0) 1 2.969 (2.692-3.276) <0.001 Definitive Tx (Ref = No Surgery) Surgery Alone Surgery, XRT within 6 months Surgery, XRT after ≥6 months 0.474 (0.412-0.546)0.310 (0.199-0.482)0.360 (0.223-0.582) <0.001<0.001<0.001 Hormone Therapy (Ref = No) Yes 0.901 (0.799-1.016) 0.088 Chemotherapy (Ref = No) Yes 1.198 (1.044-1.376) <0.001