Estrogen Benefits Breast Cancer Patients

New data presented at the 31st Annual San Antonio Breast Cancer Symposium suggest that estrogen therapy may be beneficial to controlling metastatic breast cancer. For women that had “developed resistance to standard estrogen-lowering therapy… a daily dose of estrogen could stop the growth of their tumors or even cause them to shrink.” This goes contrary to popular convention in which patients are given drugs to minimize the hormone to avoid the growth of breast cancer.

Oncologist Matthew Ellis, MB, PhD, from the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital, explained that “estrogen therapy offers an appealing alternative to chemotherapy for metastatic breast cancer that has become resistant to estrogen-lowering agents called aromatase inhibitors, such as exemestane, anastrazole and letrozole.”

In the study, participants—all postmenopausal and averaging age 59—were measured to see how well their aromatase inhibitor therapy-resistant mestastic breast cancer reacted to estrogen therapy. “Both the high- and low-dose treatments led to stabilization or shrinkage of metastatic tumors in about 30 percent of the participants.” The main difference was that the high-dose regimen was accompanied by significant side effects, such as vomiting, nausea, fluid retention, vaginal bleeding, and calcium imbalances. The low-dose regimen on the other hand had few side effects and was generally better tolerated.

Additionally, researchers found that “if study participants eventually experienced disease progression on estrogen, they could go back to an aromatase inhibitor that they were previously resistant to and see a benefit — their tumors were once again inhibited by estrogen deprivation.” When those effects ware off after several months, the researchers hypothesize that the tumors might again respond to estrogen therapy. “Some patients have cycled back and forth between estrogen and an aromatase inhibitor for several years, thereby managing their metastatic disease.” A PET scan was able to predict whose tumor would be responsive to estrogen therapy.

Ellis is optimistic that estrogen therapy might be a preferable option to chemotherapy, stating in a press release that “unlike chemotherapy, estrogen enhances the quality of life. For many of our patients, their hot flashes disappear, and they lose other symptoms of menopause. It’s a natural treatment for breast cancer. Not only that, it’s much cheaper than chemotherapy, costing less than a dollar a day.”

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For more highlights from the San Antonio Breast Cancer Symposium, check out our Conference 360 coverage.