Meanings of Expression of Vascular Endothelial Growth Factor in Thyroid Tumors

Abstract

Background: Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), is an angiogenic factor that plays important roles in tumor growth. Angiogenesis studies on VEGF deal with various types of malignant tumors, but little is known about the role or significance of VEGF in human thyroid neoplasms. Therefore, this study was performed to determine whether the VEGF expression in different histological types of thyroid tumors is altered and to see if there was a relationship between the expr ession of VEGF and either metastasis or the invasiveness of thyroid carcinomas. Methods: Forty-two cases that underwent thyroidectomy at Kosin Medical Center, between March, 1999 and February, 2000, were included in this study. Of the 42 cases, 27 were malignant (26 papillary carcinoma, 1 Hurthle cell carcinoma) and 15 were benign lesions. The expression of VEGF was determined by immunohistochemistry using paraffin embedded thyroid tissue blocks, and was quantified as negative (absent), + (1~24%), ++ (25~49%), +++ (50~74%) and ++++ (≥75%), according to the extent of positive cells. Results : VEGF was stained with red-brown colored granules in the cytoplasm of the thyroid tumor epithelium and was expressed in 27 of the 42 cases (+ 1, ++ 8, +++ 5, ++++ 13). Most malignant tumors (24 of 27 cases) were stained with VEGF, but only 3 of the 15 benign tumors cases were stained (P <0.001). When the VEGF expression was divided into ++ or below and +++ or abo ve groups, the expression of VEGF was much more extensive in the malignant than benign tumors (P <0.001). Of the 27 malignant tumors cases, lymph node metastasis and/or invasion was noted in 13. VEGF expression was more extensive in malignant tumors with lymph node metastasis and/or invasion than in those without (P <0.001). Conclusion: In this study, the rate and extent of VEGF expression were greater in the malignant than the benign thyroid tumors, and also the extent of VEGF expression was the extent of VEGF greater in the malignant tumors with lymph node metastasis and/or invasion than those without (J Kor Soc Endocrinol 20:134 ～141, 2005).