Clinical Features and Prognosis of Malignant Cutaneous Adnexal Tumors: A Retrospective Study Using a Japanese Database.

Malignant cutaneous adnexal tumors (MCATs) are rare. Previous population-based studies to determine the clinical features and prognosis of MCATs mainly included Caucasian patients, and the characteristics of Asian patients with MCATs have not yet been investigated. We aimed to investigate the characteristics of Asian patients with MCAT using a Japanese database. This retrospective study of patients with MCATs from 2012 to 2015 was conducted using a database linked to the Hospital-Based Cancer Registry and Diagnosis Procedure Combination data. Patient characteristics and survival data were analyzed using the Kaplan-Meier method and Cox regression analysis. A total of 1930 patients were included. The median age at diagnosis was 76 years (range, 14-107 years), and 46.3% of the patients were male. The most common histological finding was sebaceous adenocarcinoma (41.6%), followed by porocarcinoma (21.7%). The 5-year overall survival rate was 72.3% (95% confidence interval [CI]: 70.2%-74.3%). A favorable factor for overall survival was female sex (hazard ratio [HR]: 0.78, 95% CI: 0.64-0.96), while unfavorable factors were age > 80 years (HR: 4.40, 95% CI: 3.56-5.46), Stage ≥II (Stage II, HR: 1.34, 95% CI: 1.05-1.71; Stage III, HR: 3.12, 95% CI: 2.16-4.50; Stage IV, HR: 7.31, 95% CI: 4.92-10.87), and histologic findings of spiradenocarcinoma (HR: 4.66, 95% CI: 1.64-13.24). Tumor characteristics and prognosis of MCATs differed among subtypes. Moreover, we found differences between our data and those from other databases. Further investigations are warranted to explore these differences.