(P 359) RAPIDLY PROGRESSIVE, NON-METASTATIC, CUTANEOUS ANGIOSARCOMA OF FACE AND SCALP TREATED WITH HYPOFRACTIONATED RADIATION THERAPY: A CASE SERIES

Objective: Evaluate the role of hypofractionated radiation therapy in local control of rapidly progressive cutaneous angiosarcomas of the face and scalp.

Methods: We reviewed cases from 2015-2024 of cutaneous angiosarcoma treated at our institution, Oregon Health and Science University (OHSU), for cases of rapidly progressive lesions on the face and scalp, who received treatment with hypofractionated radiation therapy without prior surgical resection.

Results: We identified 4 cases in 3 patients of cutaneous angiosarcoma on either the face or scalp. In all cases, patients were not surgical candidates, had progression on systemic therapy, and were treated to at least 50 Gy in 20 or 25 fractions. There was excellent local control in all 3 cases (Figure 1). In case 1, a primary angiosarcoma of the right cheek progressed through systemic therapy with paclitaxel and was treated to 50 Gy in 20 fractions with excellent local control. The same patient developed an angiosarcoma on the left cheek 5 years later which was treated to 50 Gy in 25 fractions and a sequential boost of 10 Gy in 4 fractions. He had no evidence of local recurrence. In case 2, a primary angiosarcoma of the lower lip progressed through treatment with paclitaxel and the patient was started on pembrolizumab. However, immunotherapy was stopped due to GI toxicity. The tumor was treated to 50 Gy in 20 fractions with complete, and sustained tumor response. In the third case, a large angiosarcoma of the scalp that progressed through paclitaxel and immunotherapy was treated with RT to 50 Gy in 20 fractions. Again, this dosing regimen had excellent local control.

Conclusion: While angiosarcomas have been classically considered radioresistant, and thus surgical resection is often recommended, our case series highlights that radiation alone can provide excellent local control in a subset of this disease. This is particularly notable for head and neck angiosarcomas, where the morbidity of surgery can be high, particularly in the elderly population most at risk of developing angiosarcoma. Further work is warranted to assess if angiosarcomas of the face and scalp exhibiting exuberant growth may represent a unique subset of angiosarcomas for which high doses of radiation therapy may be sufficient for local disease control.