Background: Vascular endothelial growth factor (VEGF-A) expression is upregulated in the majority of human tumors, where it stimulates proliferation, migration, and survival of endothelial cells. Studies have suggested that VEGF inhibitors can be used as an alternative therapy in medullary thyroid carcinoma (MTC), but data about expression of VEGF-A and its receptor in this tumor are scarce. The aims of this study were to evaluate VEGF-A, VEGF receptor (VEGFR)-1, VEGFR-2, and microvessel density (MVD) expression in MTC samples and correlate it with clinical parameters.
Methods: Paraffin-embedded samples from 38 MTC patients were evaluated for VEGF-A, VEGFR-1, VEGFR-2, and MVD expression by immunohistochemistry. Clinical data were retrospectively reviewed in medical records.
Results: Thirty-eight patients aged 31.8 +/- 17.1 years were enrolled. Twenty-seven patients had hereditary disease (71.1%). Twenty-five of them were found to have multiple endocrine neoplasia (MEN) 2A and two were found to have MEN 2B. VEGF-A immunohistochemical staining was detected in 95% (36/38), VEGFR-1 in 96% (36/37), and VEGFR-2 in 91% (31/34) of MTC samples. Age at surgery was positively correlated with VEGFR-2 (p = 0.003). There was no correlation between VEGF-A, VEGFR-2, and tumor stage (tumor node metastasis). Nevertheless, VEGFR-1 was found to be inversely correlated with tumor node metastasis (p = 0.034). We also observed a trend toward an association between VEGFR-1 signal intensity and cure of disease, although this did not reach statistical significance (p = 0.054). Neither VEGF-A nor VEGFR-2 was associated with disease outcome after a median follow-up period of 5 years (p = 0.882 and p = 0.236, respectively). As expected, MVD was correlated with age at surgery (p = 0.005) and tumor size (p = 0.03). Patients with the hereditary form of the disease had a stronger intensity for VEGFR-1 (p = 0.039), whereas patients with sporadic disease displayed higher MVD counts (44 [27-63] vs. 21 [9-49], p = 0.018).
Conclusion: The VEGF-A, VEGFR-1, and VEGFR-2 immunoreactive proteins are overexpressed in MTC lesions and might be implicated in tumor progression. It is not clear, however, if expression of these molecules provides prognostic information regarding the spread or outcome of MTC.