Outcomes of Interventions for Angiosarcoma.

Objective: Angiosarcoma is a rare malignant vascular tumor, and the management and outcome of this disease are not well-described. The aim of this study was to report the incidence, patient demographics, and outcomes of angiosarcoma based on national data. Methods: Data on patients with angiosarcoma were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Inverse probability treatment weights (IPTW) were used to assess the survival benefit of operation with additional chemo or radiation therapy compared to operation alone. These variables were further compared against patients who did not receive an operation despite being initially offered one. Cox regression was used to assess survival. Statistical analyses were performed on RStudio. Results: For this study, 5,135 patients (46% men; median age 69, range 0-102) with angiosarcoma were identified in the SEER database between 1975 and 2016. The age-adjusted incidence rate was 1-4%. Patients were mostly non-Hispanic Caucasian (75.4%). The average tumor size was 4.7 cm, range (.1-98.9). Tumor grades were high at presentation (Grade III 17.2, Grade IV 19, and unknown 50.6%), but half were considered localized tumors. Most patients underwent an operation (66.1%). In 5.6% of patients, the operation was recommended but not performed. The overall 5-year survival was 26.7% (95% CI 25.4-28.1%). IPTW with adjusted Cox proportional hazard model demonstrated worse survival, showing that operation compared to no operation and operation with chemo/radiation compared to operation alone had worse survival between months 0 and 25 but had improved survival after month 25. Conclusions: The incidence of angiosarcoma is low and long-term survival is poor. Multimodal therapy in the form of neoadjuvant or adjuvant chemo/radiation therapy offers significant long-term survival benefits over operation alone.