Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

No link between estrogen-only therapy, breast cancer in postmenopausal women

12.04.2006


There’s a tangle of information about the pros and cons of using hormones to relieve the symptoms of menopause, but a new analysis of data generated by the Women’s Health Initiative confirms that one cause of concern can be laid to rest: There is no evidence that taking estrogen alone increases the risk of breast cancer in postmenopausal women.



The findings come three years after a related WHI study found that a different type of hormone therapy - which combined estrogen and progestin - did result in a higher risk of breast cancer among postmenopausal women.

Marcia Stefanick, PhD, a Stanford University School of Medicine researcher who oversaw the latest WHI findings, said she hopes the results provide some clarity.


"The clinical trial results for estrogen-alone and for estrogen-progestin are very different - WHI is not flip-flopping," said Stefanick, professor of medicine at the Stanford Prevention Research Center and lead author of the study to be published in the April 12 issue of the Journal of the American Medical Association. "The use of estrogen-progestin clearly showed an increased risk for breast cancer; estrogen-only therapy shows no evidence of an increased risk."

The WHI is a 15-year, broad-based look at the causes and prevention of diseases affecting older women. In addition to hormone therapy, other WHI studies have examined heart disease, breast and colon cancer, and osteoporosis.

For the estrogen-alone arm of the study, which was stopped in 2004, researchers tracked nearly 11,000 women nationwide for about seven years. The women were between the ages of 50 and 79, and had previously undergone a hysterectomy. Half of the women were given a form of estrogen known as conjugated equine estrogens, while the other half were given a placebo.

In the latest analysis, researchers found no evidence that estrogen increased the risk of breast cancer. The women taking estrogen had fewer breast tumors (28 per 10,000 cases per year) than those in the placebo group (34 per 10,000 cases), but the difference of six fewer cases per 10,000 women per year was not deemed statistically significant, meaning that it could have occurred by chance.

Still, Stefanick added that other aspects of the WHI findings suggest women taking estrogen should have additional mammograms and breast biopsies to confirm that no breast cancer is present.

These results are markedly different from those arising from the estrogen-progestin arm of the study, in which a different group of postmenopausal women taking the combined hormone therapy were found to have a 26 percent increase in their risk for breast cancer.

Stefanick noted that it’s important for women and physicians to distinguish between the two studies: the women in the combined estrogen-progestin trial still had their uteruses. Because estrogen-alone therapy increases the risk for endometrial cancer, women who haven’t had a hysterectomy and who need relief from menopausal symptoms are also given progestin, which offsets the risk of that cancer.

The estrogen-progestin arm of the WHI study was called to an early halt in 2002 - three years ahead of schedule - when evidence from the trial showed that in addition to a higher risk of breast cancer, the women taking the combined hormone therapy also had a greater risk of stroke, blood clots and, in the first year of treatment, heart attack.

The estrogen-alone study was stopped in 2004, one year before its scheduled conclusion, because of concerns that estrogen increased the risk of stroke and blood clots. Stefanick and her colleagues pointed out that even though such risks increased with estrogen-alone therapy, the absolute risk for developing one of these conditions remained relatively low. She also said the initial data indicated that the risks of taking estrogen did not appear to outweigh the benefits, which included relief from menopausal symptoms, stronger bones and the suggestion of a decreased risk of breast cancer.

Stefanick said she understood why officials at the National Institutes of Health halted the estrogen-only trial, though she and other researchers would have liked to continue it to determine whether the findings held true beyond the first seven years of treatment. "The trial was originally supposed to last for eight years, and even at that length we felt like we weren’t going to get all the answers that we wanted," she said. "That’s my one regret - that we didn’t take the trial to its planned end."

Since the end of both trials, Stefanick and the other WHI investigators have continued to analyze the data for a more detailed understanding of how hormone therapy affects women’s health.

Both the estrogen-alone and estrogen-progestin studies turned the conventional wisdom about hormone therapy on its head. For many years, observational studies and other evidence indicated that in addition to relieving menopausal symptoms, hormone therapy helped protect women against heart disease and bolstered their overall health. However, neither trial showed any benefit in preventing heart disease, and both trials showed hormone therapy, while having some benefits, posed substantial health risks. Since the results of those trials were announced, the use of hormone therapy has dropped dramatically.

Now, a more nuanced picture is beginning to emerge, and the latest results may provide some reassurance to women seeking relief from menopausal symptoms. Indeed, among U.S. women using hormone therapy, the largest percentage use estrogen alone, so the findings have broad applications, Stefanick said.

She emphasized that hormone therapy should be used only to relieve the symptoms of menopause and not as a method of preventing disease. The Food and Drug Administration recommends that women use the lowest hormone dose needed to achieve treatment goals and limit the duration of the therapy.

Susan Ipaktchian | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Health and Medicine:

nachricht 3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg

nachricht Better equipped in the fight against lung cancer
16.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>