Hormone Replacement Therapy: Updates from the Million Women Study Led by Prof. Valerie Beral

As reported in the NYTimes.com, recent studies in the United Kingdom has found that those who used hormone replacement therapy at menopause suffered an elevated risk of breast cancer, compared with women who used hormones only in the years following menopause.

This finding turns the accepted practices upside down! It has been generally assumed that younger women have minor hormone risk in the early stages of their menopause, at least for a while. Thus it has been believed that it is probably safe to prescribe HRT for those who are suffering from hot flashes, insomnia and other symptoms as long as they use the lowest possible dose for the shortest possible time. Some researchers have even taken this assumption further and have been testing a belief, called the timing hypothesis, that hormone treatment, if started early in menopause may help protect women from heart disease.

However, as mentioned above, the latest research findings from the British Study provides evidence of the contrary. According to this large study conducted in Britain, called the Million Women Study, it is has been found that the women thought to be at the lowest risk from hormones may actually be at the highest risk, at least when it comes to breast cancer.

Listed below are the key findings from this very large observational research project which was included more than a million postmenopausal women (approximately one in four British women who were aged 50 to 64 during the enrollment period, from May 1996 to December 2001).

  • Women who took the hormones the earliest were at the greatest risk of breast cancer–before or soon after menopause began.
  • 0.3% of women between the age of 50-59 who had never taken hormones, developed breast cancer within a year.
  • The above rate was higher, 0.46% a year, in women who started taking the most commonly used hormones — estrogens combined with progestin — five or more years after menopause began.
  • It was highest of all, 0.61% percent a year, in women who started taking the drugs <5 year after menopause began.
  • There was an increased risk even in women who took the drugs for less than five years.

The findings of the British study have been published in the The Journal of the National Cancer Institute. Even though the study was not designed to be a randomized controlled trial (read more about randomized control trials), it had a million participants making the results statistically very unlikely to be incorrect.

Opinions from Other Researchers about the Findings

Dr. Rowan Chlebowski, an investigator in the Women’s Health Initiative and a medical oncologist at the Los Angeles Biomedical Research Institute, believes that the study provided “substantial support” for the findings from other studies. He said the new findings made it even harder to determine what could be safe timing or duration for use of hormone.

However, Dr. JoAnn E. Manson, also an investigator on the Women’s Health Initiative and a professor of medicine at Harvard Medical School and Brigham and Women’s Hospital, alarmed that the Million Women findings were not the absolute as the study was observational.

This study will surely create more debate on whether HRTs are safe or not and if they should even be prescribed. Please share your thoughts and concerns below

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