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.
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