National epidemiology of digital papillary adenocarcinoma in England 2013-2020: a population-based registry study.

Background: Digital papillary adenocarcinoma (DPA), formerly known as aggressive DPA, is a rare adnexal cancer of sweat gland differentiation with metastatic potential. DPA epidemiology and patient outcome data are prerequisites for developing diagnostic and therapeutic guidance, which are lacking for this rare cancer.

Objectives: To report the incidence, patient demographics and treatment of patients with DPA in England from 1 January 2013 to 31 December 2020 using national cancer registry data.

Methods: DPA diagnoses in England during 2013-2020 were identified from the National Cancer Registration and Analysis Service dataset using morphology and behaviour codes. These were registered from routinely collected pathology reports, along with cancer outcomes and services datasets. The 2013 European age-standardized incidence rates (EASRs) were calculated.

Results: In total, 36 cases of DPA (7 in women and 29 in men) were diagnosed. The median age at diagnosis for the cohort was 54 years (interquartile range 46-64). The most frequently affected sites were the upper limbs (81%). All patients in the cohort received surgical excisions. The EASR was 0.10 (95% confidence interval 0.07-0.14) per 1 000 000 person-years.

Conclusions: This study reports the incidence and variation of DPA in England between 2013 and 2020. DPA was more common in older men and predominantly affected the upper limbs. This finding supports the need to develop a national policy for the reporting and management of DPA as well as development of a clinical guideline.