Unpacking the WHI Study
Good morning!
Thank you all for reaching out with topics you’d like to learn more about. The winner, by far, is the much talked about Women’s Health Initiative (WHI) study.
I’m going to attempt to clear up the confusion with the study and hopefully not leave you feeling even more confused!
Warning label…this is a long read but I think you’ll gain a better understanding and hopefully walk away with some clarity.
The study was limited, the reaction by the media created mass hysteria, there was a failure from the research community to temper and explain the accuracy of the reaction and the knee-jerk result was millions of women losing out on the potential health benefits of HRT for over two decades.
Following the publication of the WHI results in 2002, a study published in Medicina shows MHT use fell from 29% in 2001 to 10–11% in 2005 among women aged 50–74 in the UK. A large decline in use was also observed in the USA (46%) and Canada (28%), among other countries.
Original goal:
The Women’s Health Initiative (WHI) hormone therapy trials were designed to determine the benefits and risks of HT taken for chronic disease prevention by predominantly healthy postmenopausal women.
The study:
More than 160,000 menopausal women took part in this study. There were 64,500 in the controlled trials and 27,500 in the randomized trials.
The 27,500 were randomized to two arms studied:
1. an estrogen + progestin arm for women with a uterus or a placebo 2. an estrogen alone arm for women without a uterus (due to hysterectomy) or a placebo.
The estrogen + progestin arm of the study was stopped prematurely when initial data revealed that postmenopausal women being administered combination (estrogen + progestin) hormone therapy had an increased risk of breast cancer and heart disease.
It’s important to note that the point of the study was conflated to be about breast cancer, when it was originally designed to allow randomized controlled evaluation of three distinct interventions:
1. a low-fat eating pattern, hypothesized to prevent breast cancer and colorectal cancer and, secondarily, coronary heart disease
2. hormone replacement therapy, hypothesized to reduce the risk of coronary heart disease and other cardiovascular diseases and, secondarily, to reduce the risk of hip and other fractures, with increased breast cancer risk as a possible adverse outcome
3. calcium and vitamin D supplementation, hypothesized to prevent hip fractures and, secondarily, other fractures and colorectal cancer
What did the WHI study really say?
Women who took estrogen and synthetic progestin (the only combo tested) had a 26% increase in developing breast cancer over women who didn’t take hormones. You can see why this would cause an initial scare, but in absolute numbers, it translated to less than one additional breast cancer case, per 1,000 women, per year.
And for the women in the WHI who had hysterectomies and took estrogen only (instead of an estrogen/progesterone combo), the breast cancer risk actually decreased.
Why the study had limitations in detecting breast cancer risk and cardiovascular protection:
There were several factors. The hormone therapy used was a synthetic combination of estrogen + progesterone, many of the participants were over 60, had pre-existing health conditions, and arguably were not the best candidates for the study.
How it was misrepresented:
The study was largely misrepresented by the media, which created mass confusion and panic among both physicians and women. News outlets across the country ran with, “Study halted. Estrogen increases the risk of breast cancer!”
And just like that, millions of women abandoned their hormone therapy, some by choice out of fear and some who were denied access through their health practitioner.
The silver lining:
There are many who are currently studying the data and collecting new data. This is a good editorial for more detail on what’s happening in this area.
There’s also a new study out of the UK showing the following:
Women who used estrogen only did not have an increased risk of developing breast cancer over non-users.
The only group of women who had an increased risk of breast cancer were those who took estrogen and a synthetic progestin.
Women who took estrogen and bioidentical progesterone had no increased risk of breast cancer.
Why didn’t the WHI find that bioidentical progesterone had no effect on breast cancer? Because they didn’t study it!
Women who have a uterus and are taking estrogen also need to take progesterone. The only form of progesterone that shows a slight increase in the risk of breast cancer are synthetic progestins.
It’s important to note that bioidentical progesterone first came to market in 1990 and was not used often or by most at the time the study was designed in 1991. Estrogen + MPA (medroxyprogesterone acetate) was the predominant form of HRT used and thus chosen. In fact, progesterone for uterine protection was relatively new at that time. Initially estrogen replacement was all that was used, but that eventually revealed the increased uterine cancer risk and a search for a protection was launched. The bioidentical molecule is large and not absorbed so alternatives were formulated. Eventually, technology allowed for micronizing the progesterone into a usable form.
So what now:
There’s no question that an entire generation of women have missed out on the benefits of HRT and suffered as a result of the bad PR the study received and the swift reaction that ensued.
And I believe there is a larger lesson to learn in the role of influence the media plays in shaping our decisions and behaviors.
I am encouraged by the recent “menopause movement” and conversations/attention around women’s health. And I’m hopeful that this translates into more funding for studies and resources.
Know the benefits and risks of hormone therapy. Consider finding a practitioner who is menopause literate and don’t be afraid to ask questions.
I’d love to hear from you! Message me on Facebook or Instagram and let me know your current challenges.
Together, we’ve got this! Courtney
