Do Estrogens Reduce Breast Cancer Risk?
Menopause is a time when women suffer from symptoms like hot flashes and sweating due to decreased levels of the sex hormones in the body. The symptoms are generally relieved with the use of estrogens. However, estrogens do have their side effects and are not always recommended.
Following hysterectomy i.e. a surgery to remove the uterus, a condition similar to menopause develops. Estrogens are used to relieve symptoms in these cases as well.
In a trial called Women's Health Initiative trial, the use of estrogens in post-hysterectomy women was studied. More than 10,000 postmenopausal women from the United States were enrolled in the study in the period between 1993 and 1998. These women were aged between 50 and 79 years, had undergone hysterectomy, and did not suffer from breast cancer. Among these, 5310 women received 0.625 mg of conjugated equine estrogen, while the rest received a placebo. The study had to be terminated earlier than planned due to an increased risk of stroke. The women were followed up for duration of around 11 years.
Researchers found that use of estrogen for around 5 to 6 years was associated with a lower incidence of invasive breast cancer in the long run as compared to placebo. Women who took estrogen and developed breast cancer were less likely to die from the cancer or any other cause as compared to those who did not take estrogens.
The benefits of estrogen in these women were mainly noticed in those at low risk for breast cancer, such as those without benign breast disease or family history of breast cancer.
The results thus indicate that women undergoing hysterectomy who are at low risk for breast cancer could undergo estrogen treatment for a duration of around 5 years. However, the researchers do not recommend the use of estrogen with an aim of reducing breast cancer risk.
Unfortunately, different studies on this topic have yielded different results. Some studies have indicated that estrogens increase breast cancer risk; others say that they do not alter breast cancer risk, whereas the current study shows a beneficial effect.
The results of the study do not apply to women who have not undergone a hysterectomy or those who take a combination of estrogen and progesterone hormones.
1. Conjugated equine oestrogen and breast cancer incidence and mortality in postmenopausal women with hysterectomy: extended follow-up of the Women's Health Initiative randomised placebo-controlled trial; Garnet et al; The Lancet Oncology; Early Online Publication March 2012