Breast angiosarcomas (AS) are rare and aggressive malignancies, categorised as primary angiosarcoma (PAS) and radiation-associated angiosarcoma (RAAS). Due to its rarity, large series of PAS and RAAS are limited. We aimed to analyse the outcome of a large cohort of angiosarcomas with emphasis on the prognostic factors, latency, margin width and significance of locoregional recurrences.

A retrospective study was conducted on angiosarcomas managed at a large UK Regional Sarcoma Centre between 2013 and 2024. Clinical, pathological, disease-free survival (DFS) and overall survival (OS) data were collected. The interval between radiotherapy delivery and the development of angiosarcoma was calculated. Cox regression models and binary logistic regression were utilised for optimal threshold values for resection margins and patient outcomes.

PAS presented at a younger age (median 31 vs 71 years for RAAS). A significant shortening of latency between radiotherapy and onset of RAAS was found (r = − 0.719, p < 0.001). DFS and OS were 59.6%, and 54.2% respectively. Smaller microscopic resection margins were significantly associated with recurrence (p = 0.001). Recurrence was a strong predictor of mortality, HR = 2.856, p = 0.005. Mean survival with and without angiosarcoma recurrences was 32.9 and 80.5 months respectively (p = 0.005). Resection margins ≥ 10 mm were significantly associated with lower rates of recurrences (p = 0.044, OR = 0.323). However, resection margin distance did not directly impact survival (HR = 1.002, p = 0. 798). Cox regression analysis showed angiosarcoma size was not a predictor of survival (p = 0.278, HR = 1.002). Neither patient age nor the angiosarcoma histological grade correlated with recurrences or patient survival. C-Myc immunohistochemistry was positive in four of nine (44.44%) PASs and in 95.52% of RAAS. Its expression did not correlate with patient survival.

Over the last decade, the number of diagnosed RAAS cases has increased with a shortening in the interval between radiotherapy and onset of RAAS. Margin status and recurrences, but not angiosarcoma grade or size, impact survival. Achieving a clear surgical margin is therefore critical for improved patients’ outcome.