|
Estrogen Therapy May Be Effective in Treating Breast Cancer Relapse
Estrogen Therapy May Be Effective in Treating Breast Cancer Relapse
Although the last thirty years have brought great advances in our knowledge of breast cancer, it's still not understood what causes the disease to develop in a certain person at a certain time. We do know that about 80 percent of breast cancers grow with the help of estrogen and/or progesterone, female hormones that are produced in the body. When these hormones attach to special proteins called hormone receptors, the cancer cells with these receptors grow. Hormone therapies, like the drug tamoxifen and aromatase inhibitors, can stop this growth by preventing the cancer cells from getting the estrogen they need to grow. However, researchers have discovered that breast cancers can become resistant to anti-estrogen therapies, and the body may need some of the hormone to fight off the disease.
Dr. Matthew Ellis, a professor of medicine at Washington University School of Medicine and an oncologist with the Siteman Cancer Center in St. Louis, and colleagues studied 66 women with advanced breast cancer who had been treated with aromatase inhibitors, including Pfizer’s Aromasin, Novartis’s Femara, and AstraZeneca’s Arimidex. “The women in the study had all experienced a relapse while on estrogen-lowering drugs, and their disease was progressing,” Ellis said in a statement. “So they were faced with undergoing chemotherapy.”
The women were given a form of estrogen called estradiol, in both high (30 milligrams) and very low doses (6 milligrams). Both doses were similar in effectiveness, halting the growth or shrinking the tumors in about 30 percent of the women. “We found that estrogen treatment stopped disease progression in many patients and was much better tolerated than chemotherapy would have been,” Ellis said.
However, those given the high dose had more negative side effects, such as headaches, bloating, breast tenderness, fluid retention, nausea and vomiting, as well as a poorer quality of life. “We demonstrated clearly that the low dose was better tolerated than the high dose and was just as effective for controlling metastatic disease,” Ellis said, adding that these side effects were limited in comparison to other treatments.
Some of the cancers later recurred, but about a third of these women then responded again to aromatase inhibitors, which suggests that the estrogen caused some of the tumors to become sensitive to anti-estrogen drugs again. “The endocrine system is a complicated system of feedback loops and, under normal circumstances, women experience wild changes in estrogen levels, depending on whether they’re menstruating, pregnant or postmenopausal,” Ellis explained. “All this is regulated in an exquisite way, which we actually understand fairly well. These results mean the feedback loops may be corrupted in some ways.” The researchers say they are planning further studies to see which group of women might benefit most from the protocol.
Some experts remain cautious about the findings, calling for further research to support the claim. “It’s an interesting observation, but it needs to be expanded into a large trial,” said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, Louisiana. “There’s probably something biologically going on here that we don’t quite understand. The question is can we translate this into really clinically meaningful responses?”
Breast cancer is the most common cancer among American women, other than skin cancer, and is the second leading cause of cancer death in women, after lung cancer. The American Cancer Society estimates that in 2009 there will be 192,370 new cases of invasive breast cancer diagnosed in the United States and more than 40,000 will die from the disease.
The findings are published in the Journal of the American Medical Association.
|
Linear Mode
