Cutaneous Angiosarcoma Survival by Anatomic Site and Race/Ethnicity: A Dual Cohort Analysis

ABSTRACT Background Cutaneous angiosarcoma (cAS) is a rare and aggressive vascular malignancy associated with poor survival. Large‐scale evaluations of prognostic factors, particularly anatomic site and race/ethnicity, remain limited. Objectives To evaluate survival outcomes in cAS according to anatomic site and race/ethnicity using complementary national datasets. Methods We conducted a dual‐cohort analysis using the Surveillance, Epidemiology, and End Results (SEER) database (2000–2023) and the All of Us Research Program (2018–2025). Patients with histologically confirmed cAS were identified and categorised by anatomic site. Kaplan–Meier analyses and multivariable Cox proportional hazards models adjusted for age, sex, and available clinical factors were performed. Results Across both cohorts, survival differed significantly by anatomic site, with head and neck tumours demonstrating the poorest outcomes. In SEER, head and neck lesions were associated with increased mortality compared with trunk tumours (HR 1.85, 95% CI 1.65–2.08), while upper extremity tumours demonstrated improved survival (HR 0.75, 95% CI 0.62–0.90). Similar patterns were observed in All of Us. Racial and ethnic disparities were also identified. In SEER, non‐Hispanic Black patients (HR 1.42, 95% CI 1.20–1.69) and Hispanic patients (HR 1.31, 95% CI 1.12–1.53) experienced worse survival compared with non‐Hispanic White patients. Limitations This study is limited by potential residual confounding, differences in covariates available between datasets, limited statistical power in the All of Us cohort, and lack of pathology confirmation by sarcoma specialists. Conclusions In this dual‐cohort analysis, anatomic site and race/ethnicity were independently associated with survival in cAS. Consistent findings across SEER and All of Us highlight persistent disparities in outcomes and the need for improved risk stratification, earlier diagnosis, and equitable access to specialised care.