Efficacy of Radiation Therapy in 106 Patients with Extramammary Paget Disease: A Retrospective Study

Purpose Extramammary Paget disease (EMPD) is rare among Asians, and the clinical value of radiation therapy for EMPD remains controversial. This retrospective study evaluated the efficacy of radiation therapy for EMPD. Methods and Materials From January 2012 to December 2021, 106 patients with pathologically confirmed EMPD with complete follow-up data were treated at Peking University First Hospital. The primary treatment was surgery combined with adjuvant radiation therapy, with radical radiation therapy for inoperable patients. The main surgical method for the primary lesion was Mohs micrographic surgery, with a few patients undergoing wide local excision. The recommended postoperative and radical radiation therapy doses were 50 to 60 Gy and 60 to 70 Gy, respectively. The primary endpoint was disease-specific survival rate; secondary endpoints included local recurrence-free survival, lymph node metastasis, and distant metastasis rates. Survival rates were determined using the Kaplan–Meier method and tested with the log-rank test. Univariate and multivariate prognostic analyses were performed using the Cox regression model. Results The study population comprised 90 men and 16 women (male-to-female ratio, 5.6:1). The median age was 66 (range, 41-85) years. The median follow-up period was 66.5 (range, 5-139) months, with a median survival time of 132 months. The 1-, 3-, 5-, and 10-year disease-specific survival rates were 96%, 92%, 89%, and 89%, respectively; local recurrence-free survival rates were 99%, 99%, 95%, and 88%, respectively; lymph node metastasis rates were 3%, 5%, 9%, and 9%, respectively; and distant metastasis rates were 4%, 10%, 14%, and 17%, respectively. Univariate analysis revealed that the depth of invasion of the primary lesion was associated with local recurrence, with dermal involvement increasing the risk of local recurrence. Multivariate analysis revealed that the N and M stages were associated with disease prognosis. Conclusion Radiation therapy is suitable for EMPD. Post-Mohs micrographic surgery radiation therapy provides excellent local control, and radical radiation therapy effectively controls tumors, including metastases.