Study: Hormone Therapy Leads to More Advanced Breast Cancer

PBS NEWSHOUR

HEALTH — October 19, 2010 at 4:05 PM EDT

By: Lea Winerman

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.”

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Author: Leslie Carol Botha

Author, publisher, radio talk show host and internationally recognized expert on women's hormone cycles. Social/political activist on Gardasil the HPV vaccine for adolescent girls. Co-author of "Understanding Your Mood, Mind and Hormone Cycle." Honorary advisory board member for the Foundation for the Study of Cycles and member of the Society for Menstrual Cycle Research.