The Risks of Estrogen

How much risk will a woman accept in return for good sex? Many women approaching or past menopause view estrogen-replacement therapy (ERT) as a fountain of youth in a pill. By pumping up blood concentrations of estrogen to near-youthful levels, ERT vanquishes the hot flashes and night sweats responsible for libido-killing insomnia and irritability. It also prevents the thinning and drying out of vaginal tissue that comes with plummeting estrogen levels, notes Dr. Margery Gass, an Ob-Gyn at the University of Cincinnati College of Medicine. After menopause, thinner, less flexible vaginal tissue can make sex so painful that the body recoils even when the heart is willing. Virtually any form of estrogen--the pill Premarin, a patch, vaginal creams or vaginal rings kept in place for three months--"improves vaginal tissue," says Gass.

Because estrogen alone stimulates the uterine lining and increases the risk of endometrial cancer, women with an intact uterus are advised to pair estrogen with progestin--which blocks this effect--in a regimen called hormone-replacement therapy (HRT). Estrogen alone has long had a dark side: it is associated with an increased risk of breast cancer. Now, in one of those you-can't-win cases, it appears that progestin may increase the risk of breast cancer even more than estrogen alone, says Dr. Ronald Ross of the University of Southern California. Scientists now think that estrogen-progestin increases the risk of breast cancer 53 percent compared with not taking hormones; estrogen by itself raises the risk 34 percent. The longer a woman takes HRT, the greater her risk.

The standard retort to concerns about breast cancer has been, "Sure, but estrogen reduces the risk of osteoporosis." That remains pretty much unquestioned: estrogen decreases the amount of bone that is resorbed in the constant process of skeletal building and demolishing. But estrogen's killer app is supposed to be preventing heart disease. It lowers bad LDL cholesterol and raises good HDL. (Creams and rings are not effective because their estrogen is absorbed directly by the bloodstream, bypassing the liver, where cholesterol levels are adjusted.) That heart benefit was supposed to swamp the risk of breast cancer, especially since heart disease kills nine times as many American women every year as does breast cancer. But results of the newest, best-designed studies are dismaying. They find that HRT provides no heart benefits to women with existing cardiovascular disease; it may actually increase their risk of heart attacks. And it may not protect healthy women from developing heart disease: in April, researchers at the Women's Health Initiative, run by the National Institutes of Health, warned that HRT seems to raise the risk of heart attacks and stroke in healthy women, at least initially. "Women with heart disease should not take estrogen with the expectation that it will help their heart," says Dr. David Herrington of Wake Forest University. Not even great sex can fix a broken heart.