Clinical Characteristics, Treatment Patterns, and Survival Outcomes of Cutaneous Angiosarcoma in Japan: A 3‐Year Analysis of the Japan Skin Cancer Registry Study ( JSCaRS )

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.