Outcomes of lymph node dissection in the treatment of extramammary Paget's disease: A single-institution study.

Extramammary Paget's disease (EMPD) often invades the dermis and metastasizes to the lymph nodes. Patients with EMPD associated with lymph node metastases have poor prognosis; to date, effective treatment has not yet been established. Lymph node dissection, aiming to control the local disease, is a standard form of management for EMPD patients with lymph node metastases (LNM). We investigated the clinical and pathological features, treatment strategies and prognostic factors of patients with metastatic EMPD who underwent lymph node dissection. We retrospectively evaluated 38 cases of extramammary Paget's disease with lymph node metastasis over 10 years. All patients underwent wide resection of the primary lesion and lymph node dissection. Univariate analysis revealed the number of metastatic nodes and lymphadenopathy as prognostic factors. In multivariate analysis, the number of metastatic lymph nodes retained statistical significance (hazard ratio, 35.3; 95% confidence interval, 3.23-387.0; P = 0.003). The 5-year survival rate was 100% and 19.1% in patients with two or less LNM and with three or more LNM, respectively. In patients with three or more LNM, the 5-year survival rate after adjuvant radiation therapy was better than that after surgery alone (75% vs 0%). In conclusion, patients with two or less LNM can be expected to have long-term survival with lymph node dissection only, while patients with three or more LNM may require adjuvant radiation therapy to improve prognosis. These results suggest that lymph node dissection may be a strategy to treat EMPD with regional LNM.