Researchers have raised doubts about whether hormone replacement therapy increases women's risk of breast cancer. A large study, the Women's Health Initiative, found such a risk for women who used estrogen plus progesterone. After that study was published in 2002, use of hormones dropped dramatically. Breast cancer rates also fell. Some experts thought the decline in hormone treatment was the reason. But the new study disagrees. The authors took another look at data from this study and two others. They found that the drop in breast cancer rates started in the late 1990s and ended after 2003. They concluded that the evidence is not strong enough to say hormone treatment causes breast cancer. An editorial published with the study agreed. The author said today's lower doses of hormones should be compared with placebo (fake) pills in a new study. But an American Cancer Society official said there's more evidence of risk with hormones than just the studies in the new analysis. Most doctors now use hormones in the smallest doses and for the shortest time needed to treat menopause symptoms. The Journal of Family Planning and Reproductive Health Care published the study. HealthDay News wrote about it March 14.

By Howard LeWine, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Hormone therapy for women near, during and after menopause has had more ups and downs than a roller coaster ride.

Before 2002, most doctors told women to take replacement hormones to treat menopause symptoms. For most women, this meant estrogen plus a form of progesterone.

In 2002, everything thing changed -- quickly. The reason was the results of a large randomized clinical trial, the Women's Health Initiative (WHI). Randomized trials are considered the gold standard of medical studies. This type of study takes a group of people who are similar and randomly assigns them to one sort of treatment or another.

WHI assigned women to take a hormone pill called Prempro or a placebo. In 2002, the study was stopped earlier than planned. Early results suggested the health risks of hormone therapy were too high. It would not have been ethical to continue.

Older studies had suggested that estrogen helped to protect against heart attack and stroke. Researchers had expected the WHI trial to confirm those findings. It didn't. If anything, it suggested a higher risk of heart attack and stroke from estrogen plus progesterone.

The results of other large studies also suggested the risks of hormone therapy after menopause were too high. What worried many women even more than heart disease was the reported increased risk of breast cancer.

During the last few years, experts have looked again at all the study results. Many of them say we have scared women too much about the risks of hormone therapy. For example, it was reported that hormone therapy increased the risk of breast cancer by 25%. But that translates to only 1 extra case of breast cancer per 1,000 women.

That increased breast cancer risk also applies only to women who take the specific estrogen and progesterone in Prempro. Women who take only estrogen at the start of menopause may actually have a lower risk of breast cancer.

Dr. Samuel Shapiro and his colleagues in South Africa have taken another look at the breast-cancer risk related to hormone therapy.

It has been reported that the rate of breast cancer dropped significantly around the time most women stopped taking hormones in 2002. But Dr. Shapiro found that the facts don't completely support this conclusion. The evidence is just not solid enough to say the decline was directly related to the decrease in hormone therapy.

What Changes Can I Make Now?

Women who need estrogen therapy for symptoms of menopause should feel even more reassured. The best advice is to take the lowest dose that controls symptoms. From time to time, perhaps every one to two years, try to stop it and see what happens.

For women who have had a hysterectomy, the preferred treatment is estrogen only to control symptoms. There is some evidence that an estrogen patch may have a slightly lower risk of blood clots than pills.

For a woman who still has a uterus and needs control of menopause symptoms, most doctors recommend a low-dose estrogen plus a form of progesterone. Progesterone offsets the slight increase in uterine-cancer risk from taking estrogen.

What Can I Expect Looking to the Future?

In the near future, you can expect doctors to still recommend against long-term hormone therapy to help maintain health and prevent disease. But this might change for younger women just entering menopause.

New evidence suggests that estrogen therapy in younger women after menopause might actually help them prevent coronary artery disease. It also might decrease their risk of breast cancer. It's already well known that estrogen therapy at the beginning of menopause decreases the risk of osteoporosis. It may decrease the risk of colon cancer and dementia as well.