Oestrogen Receptor Positive Metastatic Eccrine Porocarcinoma: A Case Report and Review of Anti-Oestrogen Therapy in Rare Cancers

Abstract

<b><i>Introduction:</i></b> Rare cancers, in aggregate, represent a significant burden of disease in oncology and remain therapeutically challenging to manage due to a lack of clinical trials. Eccrine porocarcinoma is a rare cutaneous sweat-gland malignancy for which there remains no standard approach to metastatic disease. <b><i>Case Presentation:</i></b> We describe a patient diagnosed with metastatic disease, confirmed on bone biopsy; pathological analysis further revealed this was oestrogen receptor positive. She was commenced on the aromatase inhibitor letrozole, and denosumab, and showed a significant clinical and radiological response on bone scan within 7 months. At the time of report, over 2 years since commencing letrozole, she remains well with no evidence of progression. <b><i>Conclusion:</i></b> Our experience adds to the literature suggesting anti-oestrogen therapy can have significant benefit in patients with ER-positive non-breast cancer and is in keeping with increasing interest in therapies agnostic to site of origin but guided by expression/mutation of oncogenic drivers.