Fibroblast-activation protein (FAP) is a type Ⅱ transmembrane serine protease and is
overexpressed in cancer-associated fibroblasts (CAFs). CAFs are the predominant component in
the stroma of epithelial neoplasms. FAP can be detected in various of malignant neoplasms and
is associated to tumor cell migration, invasion, and angiogenesis. Recently, a novel
molecular probe, gallium 68-labelled FAP inhibitor (68Ga-FAPI), has been developed and used
for visualization of tumor stroma by targeting FAP. Recent studies show favorable diagnosis
efficiency in a variety of tumors, especially in gastrointestinal cancer, but the previous
studies were all small-sample data or case reports. Therefore, further large-size research is
necessary to confirm the advantages of 68Ga-FAPI in various of malignant tumors.