This month, a shocking new study concluded Hormone Replacement (HRT) is safe and DOES NOT cause breast cancer. This new Lancet Oncology study reports the long term follow up for the Women's Heath Initiative Study which was originally published in JAMA in 2004. (1-4)
The Original 2004 WHI Report - 6.8 years of Follow Up
The original WHI study (second arm) enrolled about 10,000 women after hysterectomy. Half were given placebo, and the other half were given a horse estrogen called Premarin (see above left image courtesy of wikmedia commons). Premarin is also called CEE for Conjugated Equine Estrogen. This is estrogen from pregnant horses.
The original report in JAMA 2004 included 6.8 years of follow up showing 23% Less Invasive Breast Cancer in the Premarin Hormone (CEE) group than in the placebo group . There were 94 breast cancer cases in the hormone (CEE) group and 124 cases of breast cancer in the placebo group. This comparison narrowly missed statistical significance.
In addition, there was 9% less heart disease, and 39% less hip fracture in the hormone treated group. The Premarin pill caused increased clotting (hypercoagulable state) resulting in increased stroke and pulmonary embolus in the Premarin Pill users, which caused early termination of the study. This is one reason why topical estrogen is preferable to pill form estrogen. Topical delivery of estradiol (bioidentical estrogen) does not cause increased coagulability, does not increase risk for CVA or stroke, is safer and the preferred delivery route.
The original WHI group of women were followed for an additional 6 years, for a total of 11.8 years of follow up, and this data was reported in Lancet Oncology by Garnet L Anderson PhD, and Rowan T Chlebowski (3,4). Here is what they found.
After 11.8 years of follow up, the Premarin (horse estrogen) had 151 cases of invasive breast cancer and the placebo group had 199 cases. This represents a 23% reduction in breast cancer in the hormone treated group. This was statistically significant. (P=.02)
63% Reduction in Mortality From Breast Cancer
In addition, in the hormone treated group, there was a 63% per cent reduction in death from breast cancer. 16 women died from invasive breast cancer in the placebo group, compared to only 6 in the hormone treated group.
Editorial by Howell and Cuzick
In an editorial in the same issue of Lancet Oncology, the Drs Anthony Howell and Jack Cuzick review the findings and conclude that the benefits of estrogen HRT include:
2) Reduced Risk of All Cause Mortality with improved survival numbers in the hormone treated group.
3) They advise women to avoid PremPro (the combined HRT pill ) which adds in a synthetic progestin, as the synthetic progestin IS associated with increased breast cancer.