AbstractAimsTissue factor pathway inhibitor (TFPI)‐2 has recently emerged as a serodiagnostic marker for patients with epithelial ovarian cancer (EOC), especially clear cell carcinoma (CCC). This review discusses the biological properties of TFPI‐2 and why serum levels are elevated in CCC patients.MethodsA comprehensive literature search was conducted in PubMed up until March, 2021.ResultsTFPI‐2 is a Kunitz‐type protease inhibitor and negatively regulates the enzymatic activities, such as plasmin. TFPI‐2 has been characterized as a tumor suppressor gene and was frequently downregulated through promoter hypermethylation in various human cancers. In contrast, TFPI‐2 was overexpressed only in CCC. TFPI‐2 may be involved in the pathophysiology of CCC, possibly through regulation of coagulation system, stabilization of extracellular matrix (ECM), and induction of intracellular signal transduction. TFPI‐2 suppresses tissue factor‐induced hypercoagulation in a hypoxic environment. TFPI‐2, secreted by CCC cells, platelets, and adjacent vascular endothelial cells, may suppress tumor growth and invasion through ECM remodeling. Nuclear TFPI‐2 may suppress matrix metalloproteinase production via transcription factors and modulate caspase‐mediated cell apoptosis. CCC cells may upregulate the TFPI‐2 expression to adapt to survival in the demanding environment. TFPI‐2 is secreted by CCC cells and enters the systemic circulation, resulting in elevated blood levels.DiscussionSerum TFPI‐2 reflects the overexpression of TFPI‐2 in CCC tissues and is a potential serodiagnostic marker. Further research is needed to explore the expression, clinical significance, biological function, and potential mechanism of TFPI‐2 in CCC.