Photodynamic therapy-assisted Mohs micrographic surgery for extramammary Paget's disease: A retrospective clinical study

BACKGROUND: Extramammary Paget's disease (EMPD) recurs frequently after surgery. Mohs micrographic surgery (MMS) is the standard treatment, yet discontinuous tumor growth may lead to residual lesions and recurrence. Adjuvant photodynamic therapy (PDT) may eradicate residual microscopic disease. This study evaluated the therapeutic benefit of PDT combined with MMS (PDT+MMS) for EMPD. METHODS: We retrospectively enrolled 62 patients with EMPD to compare the recurrence rate between PDT+MMS and MMS alone. To control for baseline confounding, propensity score matching (PSM) was used to construct a comparable cohort. After achieving a well-balanced cohort of 15 patients in each group, Kaplan-Meier survival analysis and the log-rank test were employed to compare recurrence-free survival between the two groups. RESULTS: In the matched cohort, the PDT+MMS group demonstrated significantly lower recurrence rates (26.7 % vs 60.0 %), significantly longer median time to recurrence (1155 days vs180 days, P = 0.04), and superior recurrence-free survival compared with the MMS-alone group (P = 0.01). Subgroup analysis suggested that PDT-assisted therapy may confer a potential benefit in prolonging time to recurrence among patients with an invasion depth > 1 mm (median time: 730 days vs 165 days, P = 0.06). CONCLUSION: After adjusting for baseline confounding factors using propensity score matching, PDT+MMS combination therapy was associated with a reduced risk of recurrence and prolonged recurrence-free survival in patients with EMPD, with a potential benefit suggested for those with deeply invasive disease (>1 mm). These findings support the potential role of adjuvant PDT in the management of EMPD, although prospective studies are warranted to confirm these observations.