TAMOXIFEN ENHANCES CELL-DEATH IN IMPLANTED MCF7 BREAST-CANCER BY INHIBITING ENDOTHELIUM GROWTH

Magnetic resonance imaging at high spatial resolution and histochemica l staining were applied to monitor the influence of tamoxifen versus e strogen on the growth, endothelial density, and extent of necrosis in tumors of MCF7 human breast canter cells implanted in nude mice. Conco mitantly with tamoxifen growth arrest, a highly significant decrease, by more than a-fold, in the endothelial density of viable tumor region s had occurred, together with a significant increase in the extent of necrosis. The results suggest that the antiestrogenic activity of tamo xifen in breast cancer, which results in enhanced necrosis and tumor r egression, is due to the inhibition of angiogenesis and of endothelial growth, thus reducing vascularization and impairing tumor perfusion.