Etoposide as Late-Line Therapy for Metastatic Extramammary Paget's Disease: A Case Series

Extramammary Paget's disease (EMPD) is a rare cutaneous carcinoma that typically arises in apocrine gland-rich areas. Advanced or metastatic disease is associated with poor prognosis and limited therapeutic options. Due to its rarity, no standard chemotherapy regimen has been established. Agents such as docetaxel, cisplatin, and 5-fluorouracil have been used, but evidence supporting their efficacy remains limited. Etoposide has occasionally been reported to provide temporary benefit in advanced EMPD, although its effectiveness remains poorly characterized. We report a case series of three patients with metastatic EMPD treated with oral etoposide as third- or fourth-line therapy. They had experienced disease progression despite prior therapies, including docetaxel, S-1, and low-dose FP (5-fluorouracil and cisplatin) therapy. Oral etoposide was administered at 50 mg/day for 3-4 weeks followed by a 1-2 week rest period. Additional radiation therapy was provided for metastatic lesions in two patients. Two patients achieved a partial response on imaging, while one showed stable disease. Serum carcinoembryonic antigen levels decreased markedly in two evaluable patients, indicating a biological response. The average progression-free survival was 7.7 months. Adverse events included alopecia and neutropenia in one patient, both manageable. Although all patients eventually died from disease progression, etoposide provided disease control and symptomatic relief. These findings suggest that oral etoposide may represent a feasible and relatively well-tolerated late-line treatment option for metastatic EMPD.