STEPHEN E. JONES, MD: If you're talking about recurrent breast cancer, there are a lot of different treatment options in the hormonal area. Including things like removing ovaries, which remove source of estrogen. A drug called "tamoxifen," which has been the gold standard for a long time. And a whole group of new drugs that really look, in some ways, like they might be better than tamoxifen.
As far as preventing recurrence for early breast cancer, the gold standard for 25 years has been a drug called "tamoxifen."
CATHY CONLEY: Anti-aromatase agents have been getting a lot of attention in the past and at these meetings. Can you explain what these drugs do, and how they're beneficial in breast cancer?
PAUL E. GOSS, MD: Aromatase enzyme is sitting there between androgens and estrogen. If you block the enzyme or you antagonize it with the so-called anti-aromatase drugs, they targeted at this enzyme and they shut off estrogen production.
We can divide anti-aromatase agents into aromatase inhibitors and aromatase inactivators. It's a bit technical, but it turns out to be important. What happens is the so-called "nonsteroidal" class of these drugs -- letrozole and anastrozole, or otherwise known as Femara and Arimidex --these two drugs, they inhibit the enzyme, they're competitive inhibitors.
So what they do is they compete with androgen for the enzyme site, and so they -- instead of the enzyme converting the androgen, they come into the way, they
push into the line. They occupy the line, and they can't be converted. So they inhibit the conversion of the natural androgens into the estrogen.
