Clinical Outcomes of Radiation Therapy for Angiosarcoma of the Scalp and Face: A Multi-Institutional Observational Study

SIMPLE SUMMARY: Angiosarcoma of the scalp and face (ASF) is a rare, aggressive tumor often treated with multimodal therapy, including radiation therapy (RT). This study analyzed RT outcomes and prognostic factors in 68 non-metastatic ASF patients. Median radiation dose was 66 Gy in 33 fractions (interquartile range 60–70 Gy in 28–35 fractions). Local control (LC), progression-free survival (PFS), and overall survival (OS) rates were assessed. Higher LC rates were associated with an equivalent dose in a 2 Gy fraction (EQD(2)) >66 Gy. Combining chemotherapy or surgery with RT improved PFS rates. No factors affected OS. Late grade 3+ toxicities occurred in 1% of patients, including one with a grade 4 skin ulcer. These findings suggest that higher EQD(2) (>66 Gy) and combination therapies enhance LC and PFS in ASF. Further studies are needed to optimize treatment strategies for this rare malignancy, particularly in elderly patients. ABSTRACT: Angiosarcoma of the scalp and face (ASF) is a rare, aggressive tumor often treated with multimodal therapy, including radiation therapy (RT). This study assessed RT outcomes for ASF and identified prognostic factors. Data from 68 non-metastatic ASF patients undergoing RT with or without other therapies were analyzed. Median radiation dose was 66 Gy in 33 fractions (interquartile range (IQR) 60–70 Gy in 28–35 fractions). Local control (LC), progression-free survival (PFS), and overall survival (OS) rates were calculated using Kaplan–Meier analysis. Multivariate analyses and adverse event evaluation were conducted. Median patient age was 75 years (IQR 71–80 years), with a median follow-up of 17 months (IQR 11–42 months). One-/three-year LC rates were 57/37%, PFS rates were 44/22%, and OS rates were 81/44%. Multivariate analyses showed that an equivalent dose in a 2 Gy fraction (EQD(2)) >66 Gy correlated with improved LC (HR 2.35, 95% CI 1.03–5.32, p = 0.041). Combining chemotherapy (HR 2.43, 95% CI 1.08–5.46, p = 0.032) or surgery (HR 2.41, 95% CI 1.03–5.59, p = 0.041) improved PFS. No factors influenced OS. Late grade 3+ toxicities occurred in 1%, with one patient developing a grade 4 skin ulcer. These findings suggest that EQD(2) > 66 Gy and combining chemotherapy or surgery can enhance LC or PFS in ASF. Further prospective studies are needed to determine the optimal treatment strategy for this rare malignancy, particularly in elderly patients.