Estrogen-only hormone replacement therapy (HRT), taken after hysterectomy (removal of the uterus) ups a woman's risk of breast cancer, but only after 15 years of treatment, according to a major study released on Monday.
The encouraging news comes from Nurses' Health Study which included nearly 29,000 women to be analyzed. It strengthens a recent report from the Women's Health Initiative finding no increased risk of breast cancer after more than seven years of estrogen-only hormone therapy.
The lead abstracter of the breast cancer study says it shows that women who take estrogen-only pills less than ten years “don't have to panic,” rather “longer-term users” should look at alternatives, the cancer specialist says.
Wendy Y. Chen- MD, MPH, who heads Study, says, “In long-term users of estrogen, after 15 years there was a statistically significant increased risk in hormone-receptor-positive breast cancers,” she added, “After 20 years, there was a significantly increased risk for all types of breast cancer.” Dr. Chen is an oncologist at Brigham and Women's Hospital and Dana Farber Cancer Institute, Boston, MA (USA).
Chen and fellow researchers report the findings in the May 8 issue of Archives of Internal Medicine.
The recent Boston study followed a group of female nurses who took part in a long-term study which began in 1976. During the entire study period, 934 women developed incursive breast cancers. Of these 226 had never used hormones, and 708 had used Estrogen therapy. The longer a woman used Estrogen, the higher her peril of breast cancer appeared to be.
And the women who had been using oestrogen for less than 10 years did not appear to have a higher risk than those who had never used hormones, but those who had been ng the hormone for more than 20 years had a substantially increased risk.
The Nurses' Health Study implements just to estrogen-only HRT, prescribed for women who have had undergone a surgical removal of their uteruses.
Rather, for women with a uterus, estrogen alone greatly increases the risk of uterine cancer. To avert this risk, HRT for women with a uterus balances estrogen with progesterone. However, adding progesterone to estrogen multiplies the risk of breast cancer.
Hormone receptors work like ears or antennae on a cell. Estrogen sends signals through the receptors that tell breast cancer cells to grow. Cells with estrogen receptors grow and multiply when estrogen attaches to the receptors.
Scientists say the discoveries should be reassuring for women who want to take the hormone for a short time to relieve symptoms of menopause-the period marked by the natural and permanent cessation of menstruation.
