Prognostic value of treatment options for extramammary Paget’s disease: a SEER database analysis

BACKGROUND: Extramammary Paget’s disease (EMPD) is a common subtype of Paget’s disease. Still, there are lacking reports concerning its clinical features, treatment options, and prognosis. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was queried for the patients diagnosed with mammary Paget’s disease (MPD) or EMPD from 1975 to 2016. Subsequent analysis was conducted to explore incidence rate, tumor characteristics, clinical features, and survival. RESULTS: A total of 1,848 patients with EMPD and 7,106 patients with MPD were retrieved from the SEER database and included in this study. The demographics of EMPD and MPD were significantly different. Compared with MPD, EMPD had better cancer-specific survival (CSS) but worse overall survival (OS). For EMPD, age (P<0.001), male (P=0.006), chemotherapy (P=0.002), poorly differentiated and undifferentiated grade (both P<0.001) and tumor metastasis (regional: P=0.019; distant: P<0.001) were independent negative prognostic indicators. Survival analysis revealed that surgery could improve both CSS and OS for EMPD (both P<0.001). However, neither radiotherapy (P=0.013 and P<0.001) nor chemotherapy (P=0.007 and P<0.001) did not exhibit favorable prognostic benefit. CONCLUSIONS: EMPD had distinct clinical features from MPD. Age, gender, chemotherapy, tumor grade and stage are independent prognostic factors for EMPD. While surgery’s protective role was supported, radiotherapy and chemotherapy could be unfavorable treatments concerning EMPD prognosis.