1.   Anastrazole blocks a vital enzyme in estrogen production, while tamoxifen prevents estrogen from binding to breast cells.

2.   It prevents estrogen from linking up to a receptor on the surface of cancer cells.

3.   Tamoxifen blocks this action by preventing estrogen from linking up to a receptor on the surface of cells.

4.   Tamoxifen, the top hormonal treatment for estrogen-fueled tumors, prevents estrogen from linking up to a receptor on the surface of cancer cells.