Angiogeneisis is essential process for tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is major regulator of angiogenesis. Recently, the incidence of papillary thyroid microcarcinoma (PTMC) increased because of development in diagnostic modality. Several recent reports have documented relationship of VEGF and papillary thyroid cancer. The aims of this study were to determine whether angiogenetic phenotype was changed or not changed and to evaluate the relationship between clinicopathologic features and VEGF, vascular endothelial growth factor receptor-1 (VEGFR-1), hypoxic induced factor-1alpha (HIF-1α) mRNA expression in PTMC.

VEGF, VEGFR-1, HIF-1α mRNA expression was examined by RT-PCR in 14 patients who had undergone thyroidectomy due to PTMC. The thyroid tumor tissue and adjacent normal thyroid tissue were collected in operation and preserved at -70℃ in RNA later solution. We evaluate the expression of VEGF, VEGFR-1, HIF-1α mRNA by RTPCR. The expression of mRNA was quantititated by densitometer and analyzed the relationship between clinicopathologic features and mRNA expression.

Compared to normal tissues, in PTMC we observed higher expression of HIF-1α mRNA (P=0.024) and lower expression of VEGF mRNA (P=0.002). There was no difference in expression of VEGFR-1.The patients with nodal metastasis had higher expression of the VEGF mRNA in tumor tissues than those without nodal metastasis but not significantly. The VEGF mRNA of tumor tissues in patients with thyroid capsule invasion or not were expressed similarly. The lower expression of VEGF mRNA were observed more frequently in younger patients (<40).

The expression of VEGF mRNA was lower in tumor tissue in spite of higher expression of HIF-1α mRNA. These results suggest that the reason for good prognosis and no progression to clinical cancer in PTMC was related to the unchanged angiogenic phenotype.