Most breast cancers are hormone-receptor-positive. The hormone estrogen binds to hormone receptors and in so doing can promote the growth of hormone-receptor-positive breast cancers. Hormonal therapies used to treat breast cancer work by limiting this effect of estrogen on breast cancer cells. Tamoxifen and Faslodex (chemical name: fulvestrant) block the binding of estrogen to the receptor. The aromatase inhibitors, which include Arimidex (chemical name: anastrozole), Aromasin (chemical name: exemestane), and Femara (chemical name: letrozole), interfere with the body's ability to make estrogen. Some hormone-receptor-positive cancers will come back or grow during treatment with hormonal therapy. When this happens, doctors say that the cancer has become resistant to hormonal therapy.
A study discovered a substance called TPBM, which blocks the gene signals that tell a breast cancer cell to grow when estrogen binds to estrogen hormone receptors. The researchers found that TPBM blocks those signals even in breast cancer cells that became resistant to treatment with the hormonal therapy tamoxifen. TPBM doesn't appear to have any effect on cells that don't have estrogen hormone receptors.
This is a potentially important discovery, since TPBM and substances like it could some day prove to be useful as a form of targeted therapy for hormone-receptor-positive breast cancers, especially those that have stopped responding to hormonal therapy. Much more research will need to be done before this possibility could become a reality. Still, research news like this offers hope that tomorrow will bring more and better treatment options for those affected by breast cancer.
Stay tuned to Breastcancer.org for the latest news on research that may lead to better ways to prevent, diagnose, and treat breast cancer.