STAT4 and ovarian carcinoma: The exact role of STAT4 in tumorigenesis remains unclear because high levels of STAT4 expression have been shown to promote invasion and metastasis in gastric cancer and ovarian cancer (Zhou et al., 2014; Zhao et al., 2017), and potentially predict a favorable outcome in these cancers (Li et al., 2017; Nishi et al., 2017).