Can Breast Cancer Survivors Safely Take Estrogen or Hormone Replacement Therapy?

The answer according to Dr Avrum Bluming and Dr Carol Tavris in their (2018) book, Estrogen Matters: Why Taking Hormones in Menopause Can Improve Women's Well-Being and Lengthen Their Lives - Without Raising the Risk of Breast Cancer, is a resounding "yes." These authors make the case that it is safe for menopausal women to take estrogen either in the form of estrogen replacement therapy (ERT) for women who have undergone hysterectomies, or in the form of hormone replacement therapy (HRT), i.e. estrogen plus progesterone, for women who have not undergone hysterectomies. Furthermore they believe that HRT is a reasonable option for treating menopause-associated symptoms and improving quality of life even for breast cancer survivors. In asserting this, Bluming and Tavris are swimming against the medical tide. To back up their assertion, much of their book is devoted to a review of the available, scientific research including the Women's Health Initiative (WHI) study and the HABITS study (Hormonal Replacement Therapy after Breast Cancer - is it safe).

Regarding the 2002 WHI findings and reports, Bluming states that the finding that HRT increased the risk of breast cancer was not statistically significant. Furthermore the study's sample was not representative of healthy women - nearly half of the sample were current or past smokers, more than a third had been treated for high blood pressure, and 70 percent were seriously overweight or obese. By 2005, the WHI was saying that their findings show that women taking ERT actually had a decreased risk of breast cancer. 

In 2004 the HABITS study was stopped prematurely after only 434 women were enrolled, because after two years, 17.6% of the HRT group and only 7.7% of the non-HRT group developed new breast cancers. There were no new breast cancers in women taking estrogen alone and the increased risk for the women on HRT turned up only among those who were also taking tamoxifen. Despite their being significant problems with the design of this study including the lack of uniformity in the choice of hormone regimen, it was regarded as having lent significant weight to the WHI findings.

Bluming also cites the results of other research studies, including six that were done in the United States, in which treating breast cancer survivors with HRT did not increase their risk of recurrence of breast cancer when compared to matched control subjects. He conducted his own pilot study over a fourteen year period, in which he followed 248 women whom he had given HRT. His goal was to determine if these women showed an increased incidence of breast cancer recurrence in the same breast, developed cancer in the other breast, or developed breast cancer metastases elsewhere in the body. What he found is that they did not. A few did have a recurrence of breast cancer, but not at a rate higher than the comparable women who were not on HRT.  

Most research stopped after the WHI results were published, but some investigators continue to evaluate existing studies. In 2006, Dr. Pelin Batur and her colleagues at the Cleveland Clinic published a review of fifteen studies totaling 1,416 breast cancer survivors using HRT compared with a cumulative control group totaling 1,998 patients. The majority of the women in the HRT group began using HRT between two and five years following their diagnosis. On the average, they remained on HRT for three years. Compared to the control group, the women on HRT had a 10 percent decreased chance of recurrence of breast cancer and a slightly reduced mortality rate from cancer and other causes.

We know that hormone therapy for menopausal women has enormous benefits including protection against heart attacks, strokes, bone fractures, diabetes, colon cancer, depression and Alzheimer's disease. According to Dr. Harriet Hall, by the 1990's, the evidence indicated that estrogen reduced the risk of heart disease by 40-50%, hip fractures by 50%, colon cancer by 50%, and Alzheimer’s by 35%. With benefits like these and research results like the ones cited in the Bluming/Tavris book, it's clear that the question of treating menopausal women with hormones needs to be revisited. Additional carefully designed and controlled large scale studies are needed to determine as precisely as possible, what the risks of taking hormone therapy are, for whom and under what circumstances.

Unfortunately most members of our medical community seem to believe that this issue is settled. It may take a lot of women and a lot of physicians bringing up the topic of hormone therapy with their physicians, colleagues and friends to get the matter reopened. Go for it ladies! The quality of women's lives depends on it!



Bluming, A. & Tavris, C. Estrogen Matters: Why Taking Hormones in Menopause Can Improve Women's Well-Being and Lengthen Their Lives - Without Raising the Risk of Breast Cancer

Hall, Harriet. 09/04/2018 blog post in Science Based Medicine.org