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Experts evaluate relevance of disputed data on HT, breast cancer
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When the results from the Women’s Health Initiative, Collaborative Reanalysis and Million Women Study trials were released more than 10 years ago, the safety of hormone therapy was challenged. Clinicians thought twice before prescribing therapies to menopausal women based on data pointing to an increased risk for breast cancer. These findings subsequently led to a decreased use of these therapies; however, the risk remains a debate among health care providers, patients and advocates.
In a critique of the three studies, Samuel Shapiro, MD, and colleagues from the department of public health and family medicine at the University of Cape Town Medical School in South Africa evaluated the reported trends on the incidence of breast cancer. The critique was published in the Journal of Family Planning and Reproductive Health Care.
Shapiro and colleagues wrote that the evidence to suggest a relationship between the declines in the incidence of breast cancer after a decline in the use of HT does not adequately satisfy the criteria of time order, detection bias, confounding, statistical stability and strength of association, internal consistence, and external consistency. Furthermore, they wrote its biological plausibility is difficult to assess.
Nick Panay, BSc, MBBS, MRCOG, MFSRH, chairman of the British Menopause Society, told Endocrine Today he was drawn to the critique due to increased publicity about the three studies. Panay, also a consultant gynecologist at Queen Charlotte’s & Chelsea and Chelsea & Westminster Hospitals, wrote in an accompanying commentary that the arguments regarding the validity of the studies could go on for years. However, improving the lives of patients going through the menopausal transition should always be considered.
“What struck me about the critique is that it highlighted the possible deficiencies of the studies and therefore cast into doubt what were originally said to be cast-iron findings about risks of breast cancer, cardiovascular disease, etc,” Panay said. “What was clear to me was that if there is a risk, bearing in mind how difficult it is to prove it conclusively, then the risk is small. In the majority of women with symptoms or risk factors for osteoporosis, for instance, the benefits still outweigh the risks.”
Panay said Shapiro was putting the studies into context, given the fact that there is now a doubt about the findings and the potential, yet small, risk for breast cancer.
“The studies shouldn’t have vastly influenced the desire to prescribe women who would benefit from HT,” he said. “It’s about putting those risks into context. These studies were designed a long time ago and the preparation we used — the measurements, the data, etc — have moved on considerably since. We’re using HT in much younger women than we’ve studied in the WHI trial and it looks like the risks are even smaller.”
Moving forward, Panay suggests clinicians return to “rational prescribing,” continuing research and development to precisely determine the risks using modern preparations. – by Samantha Costa
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JoAnn Manson, MD, DrPH, NCMP
There is extensive evidence that implicates estrogen plus progestin in the risk for breast cancer, especially with longer duration. There are several observational studies, and now there's evidence from randomized trials, including evidence for increased mortality from breast cancer with long duration of estrogen plus progestin.
The findings from the WHI trial that estrogen alone was linked to a reduced risk of breast cancer, particularly, implicate the progestin, and the findings that estrogen alone did not pose these risks are intriguing. However, we need more research to confirm this and also to be sure that this is true of other formulations of estrogen because what was studied was conjugated equine estrogen, and that doesn't necessarily mean that estradiol given alone would provide the same results.
Although I believe there is compelling evidence that estrogen plus progestin in long duration will increase the risk for breast cancer, I do agree that the absolute risks are not large if a woman is having significant vasomotor symptoms that impair her quality of life and she's interested in taking hormone therapy for less than 5 years, and she's otherwise in good health.
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