Usefulness of docetaxel as first-line chemotherapy for metastatic extramammary Paget's disease.

In invasive extramammary Paget's disease (EMPD), distant metastases may develop and the condition may become fatal; however, no standardized treatment has been established. Although based on only a few cases, several chemotherapy regimens were reported to be promising. We conducted a multicenter, retrospective study to evaluate the efficacy of docetaxel for metastatic EMPD. We retrospectively collected data on 18 metastatic EMPD patients treated using docetaxel from 1998 to 2012 in 12 institutes in Japan. The following clinical data were collected: tumor response, time to progression, overall survival and adverse effects. Of those, three patients treated combined with S-1, one patient treated with weekly schedule and one patient treated combined with radiotherapy were excluded from the further analysis. All 13 patients received monthly docetaxel as the first-line treatment. The average number of treatment cycles was 9.1. Among the 12 patients with a confirmed response, seven (58%) showed a partial response, three (25%) stable disease and two (17%) progressive disease. The disease control rate (partial response + stable disease) was as high as 83%. The time to progression and median overall survival were 7.1 and 16.6 months, respectively. The 1-year overall survival rate determined by the Kaplan-Meier method was 75.0%. All adverse effects were manageable and no treatment-related deaths were observed. The high disease control rate and overall survival shown by this study suggest that first-line use of docetaxel may be a promising treatment for metastatic EMPD. A prospective clinical trial is required to confirm our results.