Supplementary Material for: Preoperative mapping biopsies with local excision in the treatment of Extramammary Paget Disease: a retrospective cohort study, systematic review and individual patient data analysis

Background: Surgical excision of extramammary Paget disease (EMPD) is associated with a high local recurrence rate. Objectives: This study aimed to assess the local recurrence rate of EMPD after preoperative mapping biopsy (PMB) with local excision.Methods: This retrospective study included patients with EMPD who were treated at our dermatosurgery clinic between January 2016 through May 2022. In addition, we retrieved individual patient data of EMPD cases from articles published in PubMed, Cochrane, Embase, and Scopus to compare recurrence rates between patients with or without PMB using Cox’s proportional hazard model.Results: In total, 146 patients with EMPD were included. Among them 109 underwent PMB. PMB was associated with a significantly reduced recurrence rate. The 5-year recurrence rate was 11.7% (95% CI, 2.1%–20.4%) in cases that underwent PMB and 45.5% (95% CI, 22.3%–61.8%) in cases that did not undergo PMB (hazard ratio, 0.23; 95% CI 0.09-0.59, p = 0.002). Conclusion: This study found that PMB before local excision significantly reduced the risk of recurrence when treating EMPD. Further studies are necessary to compare the recurrence rates of PMB, Mohs micrographic surgery and WLE for EMPD.