The new study, which was partially funded by drug manufacturer Wyeth, included more than 7,500 women from the Women's Health Initiative who took estrogen for about six years. Roughly five years after stopping treatment, the women were 23 percent less likely to develop breast cancer when compared to their counterparts who never used HRT.
Women in the estrogen group who did develop breast cancer were 63 percent less likely to die from the disease, compared to women who never took it. The lower risk of breast cancer was seen only among women without risk factors for breast cancer, such as a history of benign breast disease or a strong family history of breast cancer, the study showed.
"The story is pretty clear about estrogen plus progestin -- no matter the age of the women, estrogen plus progestin increases [the risk of] breast cancer, heart disease, stroke and blood clots," Anderson said. "These risks outweigh the benefits for all age groups."
Why estrogen alone may lower breast cancer risk while adding progestin seems to increase the risk is the million dollar question.
"There are hypotheses about the role of estrogen in breasts after a woman has gone through menopause," Anderson said. For example, "her breast tissue, including any precancerous cells, may go through changes as a result of menopause that make them susceptible to estrogen in a way that discourages cell growth."
Estrogen-only therapy is not without risks, however. For estrogen alone, the Women's Health Initiative data showed no overall effect of estrogen on heart disease, but an increased risk of strokes and blood clots.
Women are understandably confused about whether they should take hormones to treat their menopausal symptoms, and for how long they can safely use the therapy.
"The best use of estrogen-alone is in women with a hysterectomy who need relief of hot flashes and night sweats an
All rights reserved