Treatment of extramammary Paget disease with imiquimod in a real-life setting: a multicentre retrospective analysis in Spain.

Background: Topical imiquimod has been shown to be an effective treatment for extramammary Paget disease (EMPD), although available evidence supporting its use is based on case reports and small series of patients.

Objectives: To investigate the therapeutic outcomes and analyse potential clinicopathological factors associated with the imiquimod response in a large cohort of patients with EMPD.

Methods: Retrospective chart review of 125 patients with EMPD treated with imiquimod at 20 Spanish tertiary-care hospitals.

Results: During the study period, patients received 134 treatment regimens with imiquimod, with 70 (52.2%) treatments achieving a complete response (CR), 41 (30.6%) a partial response and 23 (17.2%) no response. The cumulative CR rates at 24 and 48 weeks of treatment were 46.3% and 71.8%, respectively, without significant differences between first-time and previously treated EMPD. Larger lesions (≥ 6 cm; P = 0.04) and EMPD affecting > 1 anatomical site (P = 0.002) were significantly associated with a worse treatment response. However, the CR rate did not differ significantly by the number of treatment applications (≤ 4 vs. > 4 times per week; P = 0.112). Among patients who achieved CR, 30 of 69 (43%) treatments resulted in local recurrences during a mean follow-up period of 36 months, with an estimated 3- and 5-year recurrence-free survival of 55.7% and 36.4%, respectively.

Conclusions: Imiquimod appears as an effective therapeutic alternative for both first-line and previously treated EMPD lesions. However, a less favourable therapeutic response could be expected in larger lesions and those affecting > 1 anatomical site. Based on our results, a three to four times weekly regimen of imiquimod with a treatment duration of at least 6 months could be considered an appropriate therapeutic strategy for patients with EMPD.