Backround: Paget's disease extramammary EPEM is an uncommon entity of the skin, with an insidious but aggressive clinical manifestations due to its great locoregional commitment and potential to produce metastasis and even death. HER2 is a biomarker that is currently under study due to its clinical implications in the diagnosis, evolution and prognosis of the disease. The present study proposes to identify the evidence related to the behavior of this biomarker in extramammary Paget's disease. Methods: A systematic review of literature with a meta-analytical component was performed in which the evidence of the behavior of HER2 in patients with EPEM was extracted, according to different articles published in the main database (Medline, Embase, Cochrane, Pubmed, Google Schoolar, Science Direct, tripdatabase) without time limit for the publications. Results: Of 147 articles found on the subject, 38 met criteria for inclusion, (692 patients in total, 51.1% male). HER2 protein was over-expressed in 42.77% of the cases and the amplification of the ERBB2 gene was positive in 11.1%. The dermal invasion occurred in 87.2% of the cases, while the regional metastasis and recurrence after treatment occurred in 76.8% and 93.9% respectively. The association between Her-2 expressoin and the EPEM was significat (p<0.01). Discussion: There is overexpression and/or amplification of HER-2 in EPEM with a target positivity percentage of 42%, therefore therapy with anti-HER2 target therapies should be considered as a possible new therapeutic strategy in selected cases with positivity for this marker.
