Using estrogen to combat persistent breast cancer
In some patients, hormone typically seen as troublemaker can induce cancer cells to self-destruct
By Nathan Seppa
In some breast cancer patients who have tried everything but chemotherapy, estrogen can stall tumor growth, a new study finds.
The idea is counterintuitive since estrogen acts as a growth stimulant in most breast cancers. But using the hormone as an anticancer weapon is actually an old strategy that might offer a new treatment option, researchers report in the Aug. 19 Journal of the American Medical Association. They are cautiously optimistic because a screening test used in the new study can determine with considerable accuracy which breast cancer patients would probably benefit from estrogen.
Most breast cancers are estrogen-receptor positive, meaning cancer cells in the breast often multiply when estrogen binds to receptor proteins on the cells. But the hormone’s effects on a tumor are far from one-dimensional. Estrogen can also send breast cancer cells into a spiral of programmed death. If dying cells outnumber multiplying cells, tumor growth stalls.
Indeed, synthetic estrogen was used as a treatment option for breast cancer for decades until the drug tamoxifen gained approval more than 25 years ago. Tamoxifen starves breast cells of estrogen by binding to the estrogen receptors on cells, as does a newer drug called fulvestrant. Other drugs, known as aromatase inhibitors, prevent estrogen manufacture by the body.