Radiation‐Associated Angiosarcoma Among Breast Cancer Survivors: Clinicopathologic Features and Oncologic Outcomes

BACKGROUND: Data is limited for radiation-associated angiosarcoma (RAAS) given its rarity and the tendency for investigators to combine primary and secondary breast angiosarcomas together. METHODS: This retrospective study included patients with RAAS of the breast/chest wall who received treatment at a comprehensive cancer center from 2011-2025. All patients had prior breast cancer treated with surgery and radiation therapy (RT). Clinicopathologic features, treatment patterns, and survival outcomes were collected and analyzed. RESULTS: Among 135 patients, median age at RAAS diagnosis was 68 years with median latency period of 7.5 years. Skin changes were the most common clinical presentation (90%). Multimodal treatment with chemotherapy and surgery was most common (69%); only 5 patients received re-irradiation. Among 125 patients who underwent surgery, 75 (60%) had total mastectomy and 35 (28%) had mastectomy (or completion mastectomy) with extended resection of irradiated skin. Among 78 patients who received neoadjuvant chemotherapy, 56% demonstrated complete/near-complete pathologic response (residual viable tumor < 10%). Median overall survival (OS) was 7.1 years with 5-year-OS of 60%. Longer OS was associated with surgical resection (p = 0.011) and the absence of recurrence (p < 0.001). Among surgical patients, 57 (46%) developed recurrence, most of which were local (70%). Longer recurrence-free survival was associated with receiving chemotherapy (p = 0.021), complete/near-complete pathologic response (p = 0.026), and extended skin resection (p = 0.019). CONCLUSIONS: In patients with RAAS after breast cancer treatment, improved local control was seen with more aggressive treatments, including chemotherapy (particularly in those who had robust response) and extended surgical resection. These findings may help refine current clinical algorithms for the management of RAAS.