Improved Oncologic Outcomes with Trimodality Therapy for Radiation-Associated Angiosarcoma of the Breast.

BACKGROUND: Radiation-associated angiosarcoma of the breast (RAASB) is a rare aggressive malignancy arising after breast irradiation. We previously reported that trimodality therapy showed high rates of pathologic complete response (pCR) and durable local control. Here we report an expanded cohort with longer follow-up to characterize the oncologic outcomes of this approach.

METHODS: With IRB approval, we performed a retrospective review of newly diagnosed RAASB patients operated at Mayo Clinic in Rochester 2000-2025. Trimodality therapy was defined as sequential induction chemotherapy, preoperative concurrent chemoradiation, and wide surgical resection; Mono/Dual therapy consisted of surgery +/- chemotherapy. Clinical characteristics, treatments, and oncologic outcomes were abstracted. RFS was estimated using the Kaplan-Meier method and reported with 95% confidence intervals (CI).

RESULTS: Forty-three patients (median age 68 years [40-80]) were included; 24 Trimodality therapy and 19 Mono/Dual therapy. Age and extent of presenting disease was similar between the Trimodality and Mono/Dual therapy groups. All Trimodality patients received chemotherapy, chemoradiation, and wide resection with flap closure. Among Mono/Dual patients, none had radiation, 47% had chemotherapy, and 68% had wide resection, with flap closure in 58%. Eight-year recurrence free survival was superior in the Trimodality group at 96% [95% CI 87-100%], versus 50% [95% CI 30-86%] in the Mono/Dual group, p = 0.002. Eight-year overall survival was also superior in the Trimodality group at 94% [95% CI 84-100%], versus 65% [95% CI 45-95%] in the Mono/Dual group, p = 0.047.

CONCLUSIONS: Trimodality therapy for RAASB demonstrates high rates of pCR, local control, and survival.