Table 2.

Negative prognostic factors as they were evaluated by each study

Authors/Prognostic factors	Close or positive surgical margins	Dermal invasion	Lymph node metastasis	Adnexal involvement	Tumor size	Coexisting histology of adenocarcinoma or vulvar carcinoma	Perineal involvement	Stage	Multifocality
Besa et al. 1992 [6]	+			+	+	+	+	+
Luk et al. 2003 [7]					+	+	+	+
Son et al. 2005 [8]					+	+
Tanaka et al. 2009 [9]	+	+	+
Hata et al. 2011 [10]	+	+	+
Hata et al. 2012 [11]		+	+		+
Cai et al. 2013 [2]	+	+	+	+		+			+
Hata et al. 2014 [12]		+	+		+
Hata et al. 2015 [16]		+	+		+