A comparison of protein expression between 84 low-risk (A, AB, and B1) and 116 high-risk thymic epithelial tumors (B2, B3, and thymic carcinomas) using tissue microarray analysis revealed an increased expression of VEGFA, VEGFC, and VEGFD, as well as the receptors VEGFR1, VEGFR2, and VEGFR3 in high-risk thymic epithelial tumors [92]. This evidence concerns the gene FLT1 and thymic epithelial neoplasm.