Demographics and outcomes of eccrine porocarcinoma: results from the National Cancer Database
Sara Behbahani, Stefano Malerba, Katrice M. Karanfilian, Christopher J. Warren, Albert Alhatem, Faramarz H. Samie
Abstract
Funding sources: none. Conflicts of interest: none to declare. Dear Editor, Eccrine porocarcinoma (EPC) is a rare, malignant tumour of the eccrine sweat glands. It was first described as ‘epidermotropic eccrine carcinoma’ in 1963 by Pinkus and Mehregan.1 EPC represents 0·005–0·01% of cutaneous tumours, but it is one of the most common malignant cutaneous adnexal tumours.2 Studies have been limited due to its rarity, and controversies regarding tumour behaviour and treatment are present in the literature. Previous studies have been limited to case reports, case series, literature reviews and meta‐analyses. We aimed to investigate the associations of patient demographics, tumour stage and treatment modalities with overall survival (OS) in patients with EPC using the National Cancer Database (NCDB) from 2004 to 2016. International Statistical Classification of Diseases and Related Health Problems histology code 8409/3 combined with the site and morphology primary codes for skin (C44·0–44·9) were used to identify patients in the NCDB with a diagnosis of EPC. Cases with no survival information, cases where EPC was not the primary malignancy, and cases not confirmed histologically were removed. We used Kaplan–Meier and log‐rank tests and Cox proportional hazards models to analyse the characteristics and survival outcomes of the 611 cases that met our criteria. The variables age, sex, race, primary site, surgical procedure, chemotherapy, radiation, tumour size, insurance status, treatment combination, Charlson–Deyo Comorbidity Score and tumour stage according to the American Joint Committee on Cancer (AJCC) 6th and 7th editions demonstrated significant differences (P < 0·05) on Kaplan–Meier analysis based on log‐rank testing and were included in the Cox regression. As this study included no patient identifiers, it was exempt from institutional review board approval.