Histologic Origin and Survival in Salivary Duct Carcinoma: A Retrospective Cohort Study

Abstract Objective To evaluate the impact of histologic origin on survival in salivary duct carcinoma (SDC) and characterize its clinical and pathologic features. Study Design Retrospective cohort study. Setting Single, tertiary academic medical center. Methods This study included treatment‐naïve patients diagnosed with SDC (2000‐2024). Histologic origin (ex pleomorphic adenoma [PA] vs de novo) was determined pathologically or clinically. Kaplan‐Meier analysis and log‐rank tests assessed overall survival (OS) and disease‐free survival (DFS). Cox regression estimated hazard ratios (HR) and 95% confidence intervals (CI) for 13 covariates. Results Out of N = 85 SDC patients, 68 were treated with curative intent, including 43 de novo and 25 ex PA cases. Median follow‐up was 19.8 months. OS and DFS survival were not significantly different by histologic origin (OS P = .28; DFS P = .19), though 2‐year OS and DFS were numerically higher in ex PA (OS: 87% vs 81%, DFS: 63% vs 57%). Histologic origin was not associated with OS (univariate P = .29) or DFS (univariate P = .19; multivariable P = .23). Distant recurrence was the most common failure pattern, occurring more frequently in de novo cases (37% vs 21%, P = .23). Conclusion Histologic origin was not independently associated with OS or DFS, although numerically higher 2‐year survival in SDC ex PA may suggest potential biologic differences between ex PA and de novo origins that warrant further study. Distant metastasis was the primary mechanism of treatment failure for both subtypes of SDC, highlighting the need to explore novel treatments, such as neoadjuvant therapies.