Aromatase inhibitors. Breast cancer drugs that block estrogen

mari.. Just in case no one has answered your question yet the following explains what an Aromatase Inhibitor (AI) is. I had never heard of AI's until I got breast cancer.

Aromatase inhibitors stop the production of estrogen in postmenopausal women. Aromatase inhibitors work by blocking the enzyme aromatase, which turns the hormone androgen into small amounts of estrogen in the body. This means that less estrogen is available to stimulate the growth of hormone-receptor-positive breast cancer cells.