Efficacy of chemotherapies for unresectable extramammary Paget disease: a single-centre retrospective study

Background Extramammary Paget disease (EMPD) is a cutaneous neoplasm that can metastasize to the lymph nodes and distant organs, resulting in a poor prognosis. For unresectable distant metastases of EMPD, no consensus has been reached regarding optimal chemotherapy owing to a lack of data. Objectives To evaluate the efficacy of three regimens: docetaxel (DTX) monotherapy; combination therapy with 5-FLuorouracil, epirubicin, carboplatin, vincristine and mitomycin C (FECOM); and tegafur (S-1) monotherapy. Methods This single-centre retrospective study included 32 patients diagnosed with unresectable EMPD and treated with chemotherapy between 2002 and 2022 at the National Cancer Center Hospital in Japan. Patient characteristics, responses to treatment and survival data were evaluated for each of the first-line therapies. Results Among the 17 patients who received DTX monotherapy, the response rate (RR) and disease control rate (DCR) were 47% and 77%, respectively. The median progression-free survival (PFS) and overall survival (OS) were 12.3months [95% confidence interval (CI) 6.1-26.6] and 19.2months (95% CI 8.5-not reached), respectively. Among the 11 patients who received combination FECOM chemotherapy, the RR and DCR were 55% and 64%, respectively. The median PFS and OS were 6.8months (95% CI 3.5-not reached) and 13.4months (95% CI 8.6-21.3), respectively. Among the four patients who received S-1 monotherapy, the RR and DCR were 0% and 25%, respectively. The median PFS and OS were 5.4months (95% CI 2.3-not reached) and 12.5 (95% CI 2.3-not reached) months, respectively. Conclusions Further investigations with prospective analysis are required to confirm these findings.