ABSTRACT Nationwide prospective data on the clinical management of cutaneous angiosarcoma in Japan are lacking. We analyzed 3 years of data from the Japan Skin Cancer Registry Study, a registry involving 86 institutions. Analyses were restricted to the 335 patients registered at least 12 months before the follow‐up data cutoff, a criterion independent of outcome. The median age was 79 years, 66.6% were male, and 74.0% of lesions were located on the scalp. The median tumor diameter was 8.0 cm. At diagnosis, lymph node and distant metastases were present in 14.0% and 12.5%, respectively. Radiotherapy was administered to 78.8%, systemic therapy to 72.8%, and surgery to 14.6%. The most common treatment combination was radiotherapy plus systemic therapy without surgery (54.6%). Median overall survival was 29.0 months, with 1‐ and 2‐year survival rates of 73.8% and 54.8%, respectively. Overall survival was 33.0 months without metastasis, 20.0 months with lymph node metastasis, and 10.0 months with distant metastasis. Distant metastasis (hazard ratio 2.66; 95% confidence interval 1.63–4.33), tumor diameter (1.70 per unit of log‐transformed diameter; 1.30–2.22), and age (1.03 per year; 1.01–1.05) were independent prognostic factors; lymph node metastasis (1.59; 0.96–2.61) and male sex (1.46; 0.96–2.22) were not. Two‐year overall survival was higher in the surgery group (81.5% vs. 49.6%), but was no longer statistically significant after 1:1 propensity score matching (79.7% vs. 61.6%; hazard ratio 0.53; 0.24–1.20), although survival remained numerically higher in the surgery group. The objective response rate to systemic therapy declined from 57.7% in the first line to 23.0% in the second line and 6.7% in the third line. In Japan, cutaneous angiosarcoma is most commonly managed with radiotherapy and taxane‐based systemic therapy rather than surgery. The survival advantage in the unadjusted analysis may partly reflect imbalances in background factors and selection of patients with a favorable prognosis for surgery.
