The aim of the present study was to determine the serum levels of
vascular endothelial growth factor in animals in the course of pharmacological treatment against
perianal gland neoplasms. Research material comprised of
tumor tissue samples obtained from 30 dogs and blood drawn from dogs with
tumors and control group animals. The
neoplasm type was determined in accordance with the relevant WHO classification. Immunoenzimatic determination of
VEGF levels in the blood sera was performed. In all studied animals suffering from
tumors, pharmacological
tamoxifen treatment was administered, at a dosage of 2 mg/kg bodyweight. The medication was administered for one month. In order to monitor the serum levels of 17-β-estradiol and
VEGF, blood was drawn from sick animals three times (on the day of the diagnosis, as well as at one and six months
after treatment). The
VEGF determination assay was performed in accordance with the manufacturer's guidelines for the ELISA. In the studied group, 12 animals were diagnosed with hepatoid gland
adenomas and 18 with hepatoid gland
epitheliomas. Elevated
VEGF levels were observed in the group of dogs with hepatoid gland ephithelioma in comparison with the control group. In the studied groups, a decrease in serum
VEGF level and a complete remission of neoplastic lesions was observed one month after administering
tamoxifen. The
VEGF levels in dogs with hepatoid gland
adenoma continued to decline with time. In the case of dogs with hepatoid gland
epithelioma, after the initial drop one month
after treatment, a rapid increase of the
growth factor level was observed, which was significantly higher in animals suffering a relapse of the neoplastic disease (50% of dogs). A significant correlation was observed between 17-β-estradiol and
VEGF levels in dogs with hepatoid gland
epithelioma on the day of diagnosis (Rxy=0.64, p<0.05) and six months
after treatment (Rxy=0.54, p<0.05). Conclusion:
VEGF overexpresion observed six months after
tamoxifen treatment may constitute a prognostic factor in terms of the progression of the neoplastic process. The level of
VEGF correlates with the level of 17-β-estradiol in serum. Apart from anti-
estrogen effects,
tamoxifen also demonstrates anti-angiogenic activity.