In vivo measurement of tumor estradiol and Vascular Endothelial Growth Factor in breast cancer patients

BACKGROUND: Angiogenesis, crucial for tumor progression, is a process regulated in the tissue micro-environment. Vascular endothelial growth factor (VEGF) is a potent stimulatory factor of angiogenesis and a negative prognostic indicator of breast cancer. VEGF is biologically active in the extracellular space and hitherto, there has been a lack of techniques enabling sampling of angiogenic molecules such as VEGF in situ. The majority of breast cancers are estrogen-dependent, and estrogen has been shown to regulate VEGF in normal breast tissue and experimental breast cancer. We investigated if microdialysis may be applicable in human breast cancer for sampling of extracellular VEGF in situ and to explore if there is an association with local estradiol and VEGF levels in normal and cancerous breast tissue. METHODS: Microdialysis was used to sample VEGF and estradiol in tumors and adjacent normal breast tissue in postmenopausal breast cancer patients. VEGF and estradiol were also measured in plasma, and immunohistochemical staining for VEGF was performed on tumor sections. RESULTS: We show that in vivo levels of extracellular VEGF were significantly higher in breast cancer tumors than in normal adjacent breast tissue. There was a significant positive correlation between estradiol and extracellular VEGF in normal breast tissue. However, no correlation was detected between estradiol and VEGF in tumors or between tumor VEGF and plasma VEGF. CONCLUSION: We conclude that VEGF and estradiol correlates significantly in normal breast tissue. Microdialysis may be used to provide novel insight in breast tumor biology and the regulation of molecules in the extracellular space of human breast tumors in vivo.