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Study: Hormone Therapy Leads to More Advanced Breast Cancer

Eight years ago, a major nationwide study found that post-menopausal women who took long-term hormone replacement therapy were more likely to develop breast cancer, heart disease and stroke than women who didn’t.

Now, a follow-up study released Tuesday finds that the breast cancers those women developed were, on average, more advanced and possibly more deadly than the cancers developed by women who did not take hormone therapy.

The news adds to the ongoing debate over the safety of the therapy, which many women still take to control menopause symptoms like hot flashes and sleep difficulties. From the 1980s until 2002, many doctors prescribed hormone therapy as a kind of long-term safeguard as well — it was believed to reduce the risk of heart disease and osteoporosis as well as alleviate temporary menopause symptoms.

In the original study, researchers divided 16,608 women into two groups: A group of about 8,000 women who received hormone replacement therapy (a combination of estrogen and progestin), and a control group of about 8,000 women who did not. All of the women were between 50 and 79 years old. The study began in 1993 and was intended to last until 2005, but the researchers ended it early, in 2002, when it became apparent that the risks of long-term hormone therapy use outweighed the benefits for most people.

In the new study, published Tuesday in the Journal of the American Medical Association, researchers followed 12,788 of the original participants for four more years. They found that overall, women who had taken long-term hormone therapy were more likely to develop invasive breast cancer than those who hadn’t (385 cases vs. 293 cases). They also found that among women who had taken long-term hormone therapy, the cancers were more advanced: 23.7 percent of the cancers had spread to the lymph nodes at the time of diagnosis. Among women who hadn’t taken hormone therapy, that was true for only 16.2 percent of the cancer cases.

“I use the analogy of a veil,” explains Dr. Rowan Chlebowski, an oncologist at the University of California-Los Angeles and the lead author of the study. “Combined hormone therapy increases the density of the breast and creates a more opaque view of what is actually going on — and when women were on the estrogen/progestin, you couldn’t tell what was going on until the cancers got bigger and the tumors were more advanced.”

Though the risks of long-term hormone therapy are clear, current FDA and professional guidelines recommend short-term hormone therapy as a treatment for severe menopause symptoms, and the new study does not address short-term therapy. But some scientists say that more research on short-term therapy is needed.

“The available data dictate caution in the current approach to use of hormone therapy, particularly because one of the lessons from the [Women’s Health Initiative] is that physicians are ill-equipped to anticipate the effect of hormone therapy on long-term health,” writes Peter Bach, a physician and health policy researcher at Memorial Sloan-Kettering Cancer Center, in a JAMA commentary on the study.

Dr. Chlebowski also says that the findings should spur women to be more critical when deciding whether to take hormone therapy for their menopause symptoms, and that the drugs should come with warning labels.

But some doctors say that women should not dismiss all hormone therapy, which is still considered the most effective treatment for some symptoms of menopause.

Julie Gralow, the director of breast medical oncology at the Seattle Cancer Care Alliance, points out that the women in the study were on average 62 years old — and that the results are not necessarily as relevant to, for example, a 48-year-old woman at the beginning of menopause. Also, studies have found that estrogen therapy alone does not increase breast cancer risk as estrogen-progesterone therapy does, although it can increase the risk of uterine cancer.

“What’s very clear is that women should not go on it long-term — there are bad outcomes,” Gralow says. But, she adds, “clearly there are people who feel awful going through menopause. I think it’s just fine to take estrogen in some form, minimizing progesterone, to get through a bad period.”

With reporting by Jenny Marder and Bridget DeSimone

We’ll have more on the new research tonight on the NewsHour.

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