Estrogen Plays Surprise Role in Breast Cancer...(n therapy but at a lower dose than anyth...),Health

"Giving estrogen actually was a standard-of-care practice prior to tamoxifen approval, so this trial simply confirms previously known knowledge, that estrogen can be used to treat metastatic hormone-dependent breast cancer in postmenopausal women," said Dr. Ramona Swaby, an assistant professor of medical oncology at Fox Chase Cancer Center in Philadelphia.

To try to prove the point that lower doses of estrogen might work, 66 women with metastatic breast cancer and estrogen-receptor-positive tumors were randomized to receive either 6 milligrams or 30 milligrams of oral estradiol (estrogen) each day. All women had been treated previously with an aromatase inhibitor but their disease returned.

"The 30-milligram dose produces estrogen levels typical of pregnancy, and the 6-milligram dose produces levels of non-pregnant premenopausal women [who are ovulating]," Ellis said.

The two doses were similar in effectiveness, with tumors shrinking or not growing in about 30 percent of the women.

But those taking the higher dose had more negative side effects than those in the lower-dose group, as well as a poorer quality of life, making the lower dose the overall winner.

Meanwhile, the researchers also found that they could predict which tumors would respond based on results from positron emission tomography (PET) scans taken before and after the treatment. Tumors that glowed more brightly were much more likely to respond to the estrogen treatment, according to the study.

Some of the cancers later recurred, but about a third of these women then responded again to aromatase inhibitors.

Ellis also noted that 6 milligrams of estrogen costs only about $1 a day.

No one yet knows why this effect is happens to certain women.

"The endocrine system is a complicated system of feedback loops and, under normal circumstances, wo
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