(P 24) NEOADJUVANT CHEMOTHERAPY FOR RADIOTHERAPY ASSOCIATED ANGIOSARCOMA (RAAS) OF THE BREAST IMPROVES ONCOLOGICAL OUTCOMES

Objective: Radiotherapy associated angiosarcoma (RAAS) of the breast is a rare malignancy with poor survival. Optimal treatment strategies remain uncertain due to a lack of data, and varies between surgery alone and a combination of surgery with (neo)adjuvant chemotherapy (NACT) and/or radiotherapy. The aim of this study was to evaluate the potential benefit of taxane based NACT.

Methods: In this retrospective single center study, all patients with primary RAAS of the breast treated between 1994 and 2024 are included. Since 2018, NACT is considered a treatment option for this patient population in our institute. The difference in oncological outcomes of patients with NACT was compared without NACT.

Results: Thirty-five women were included. Thirteen (37.1%) received NACT of which five (38.5%) also had neoadjuvant radiotherapy with hyperthermia. Eleven patients (84.6%) received Paclitaxel, the other two (15.4%) had Doxorubicine/Docetaxel. Complete pathological response (pCR) was found in 69.2% (n=9). Median follow up since start treatment was 32 months (range 12-89) for patients with NACT and 44 (range 6-190) for patients without. In the NACT group, one patient developed a recurrence after 6.5 years. Patients with NACT had better oncological outcomes than patients without NACT in terms of 3-year local recurrence free survival (100% vs. 63.9%), distant metastates free survival (100% vs. 47.5%), and overall survival (100% vs. 56.1%).

Conclusion: NACT for primary RAAS of the breast improved oncologic outcomes compared to no NACT. Larger, prospective, studies can validate these findings and establish the role of NACT in the management of this rare malignancy.