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Hormone Replacement Therapy Linked to Breast Cancer Increases

Study finds long-term use leads to alarming rise, but experts question the numbers

TUESDAY, Feb. 12, 2002 (HealthDayNews) -- Older women who use any type of long-term hormone replacement therapy face what appears to be an alarming risk for all types of breast cancer.

A new study reveals that post-menopausal women who used hormone replacement therapy (HRT) for five years had almost triple the risk of breast cancer compared to non-users. For women who were taking the hormones when their cancer was diagnosed, the risk almost quadrupled.

While the numbers may seem startling, cancer experts caution that the research needs to be put in context. Because the study is small and the findings so huge, they question whether the numbers are representative of all women who use HRT.

Although this isn't the first research to point out the dangers of HRT, it's the first to show it can increase the risk of all types of breast cancer.

The findings, coming close on the heels of research questioning the ability of mammograms to save lives, appear in the Feb. 13 issue of the Journal of the American Medical Association.

"The fact that we could clearly see … large risks associated with lobular [breast cancer], and at least a 50 percent increase of non-lobular [breast cancer], well, that's important because non-lobular breast cancer is by far the largest type," says study author Emily White, a researcher at the Fred Hutchinson Cancer Research Center in Seattle.

The glands that manufacture breast milk are called lobules, and the tubes that connect the glands to the nipples are called ducts. Lobular cancer starts in those milk-producing glands. While relatively uncommon, it is difficult to diagnose and treat. Non-lobular cancer usually occurs in the ducts. While it develops more frequently, it is easier to both diagnose and treat.

For hormone therapy expert Dr. Rogerio A. Lobo, the new findings aren't cause for alarm.

"I wouldn't be overly concerned with the threefold increase, mainly because it's inconsistent with a whole mound of other literature on this, and no one has shown this high a risk," Lobo, chairman of obstetrics and gynecology at Columbia Presbyterian Medical Center, says.

"If there is an association between long-term use of any hormonal preparation and breast cancer -- and I think predominantly the weight of evidence is pointing in that direction -- by far, it is the lobular cancers which are represented most," he says. The overall number of women likely to be affected is still relatively small, he explains.

The study included 705 post-menopausal women between the ages of 50 and 74. All had primary invasive breast cancer diagnosed between 1990 and 1995. There were also 692 randomly selected women of similar ages in the comparison control group. All the women were from the Group Health Cooperative in Seattle.

The cancer patients were further divided into two groups, based on cell and tissue examination of their tumors. There were 91 cases of the more severe lobular breast cancer, and 614 cases of the more common non-lobular cancer.

The researchers then reviewed pharmacy records on all the women, looking for long-term use of any type of HRT up to six years before diagnosis.

White notes that having accurate pharmacy records, rather than having to rely on a patient's memory as most studies do, gave extra weight to the findings.

Those results: An increase of 60 percent to 85 percent in all types of breast cancer among women using all types of HRT.

More specifically, long-term use of HRT, which means at least 57 months within a six-year period, translated into a 50 percent increased incidence of non-lobular breast cancer. Long-term use of combination progestin-estrogen HRT resulted in triple the risk of lobular breast cancer. Current use, which means HRT was in use at the time the cancer was diagnosed, quadrupled the risk.

While the implications are hard to ignore, what seems less clear is how women can use this information.

"My personal feeling is that the risks are becoming clearer in terms of breast cancer. The benefits of HRT, particularly in terms of heart disease, are becoming less clear. So, I think women should be more cautious about the use of HRT," White says.

Lobo says the answer is more personalized treatment plans.

"The decision to use HRT must be decided one woman at a time, and always be based on a patient's specific needs and her personal and family history of disease," he says.

Experts note other studies have shown that, even with long-term use, once a woman stops taking HRT for five years, her risk of breast cancer drops back down to that of non-users.

What To Do

For more information on breast cancer, visit The National Alliance of Breast Cancer Organizations, or go to The American Cancer Society.

To learn more about the risks and benefits of HRT, check out The National Cancer Institute.

You can also find information at The American Medical Women's Association.

SOURCES: Interviews with Emily White, Ph.D., Fred Hutchinson Cancer Research Center, Group Health Cooperative, and the University of Washington, Seattle; Rogerio A. Lobo, M.D., professor, obstetrics and gynecology, College of Physicians and Surgeons, Columbia University, chairman, obstetrics and gynecology, Columbia Presbyterian Medical Center, New York City; Feb. 13, 2002, Journal of The American Medical Association
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