Estrogen and Breast Cancer
By: Mache Seibel, MD
Estrogen; it influences a woman’s curves and develops her breasts. But every since the infamous 2002 Women’s Health Initiative (WHI) study reported that women who take estrogen plus a synthetic progesterone called Provera have an increased risk for developing breast cancer, estrogen has gotten a bad rap.
I know not only because I am a leading expert in women’s wellness and menopause, but also because 7 months after that report my wife had surgery that threw her into early menopause and her doctors didn’t want to give her estrogen. In addition to my patients, I needed to know to help my wife.
The good news is that after reanalyzing the original WHI study and the aid of many more studies since, it’s clear estrogen got a bad rap. Estrogen can be safely used to help most women.
I’m going to focus here on some important points about estrogen and breast cancer.
First, how did the 2002 authors got it wrong? As I mentioned earlier, that 2002 article wasn’t about estrogen; it was about a combination pill that included the oral estrogen Premarin plus a synthetic progesterone called Provera (PremPro). Women who have a uterus and take estrogen must also take a progestogen (progesterone or something that acts like it) to prevent the uterine lining from developing uterine cancer. Adding a progestogen prevents uterine cancer. It was the synthetic progesterone called Provera and not estrogen that caused many of those problems.
Also, the study was designed poorly. The women who received a placebo were mostly healthy and ages 50 to 59 years. The women who received the PremPro were mostly 60 to 79, and many were smokers with diabetes and high blood pressure. It’s easy to guess which group would have more health problems.
When the same data was reevaluated and only women age 50 to 59 were compared, the women who received PremPro had only a very minimal breast cancer increase – less than women on no hormones who have fibrocystic disease. The women on PremPro also lived longer than the women who got a placebo.
What about women who had a hysterectomy (had their uterus removed) and took estrogen only? Those women had a 23% lower risk of developing breast cancer than the women who received a placebo. They lived longer too. As a result, the package inserts of estrogen now say that when taken alone, estrogen results in a decreased risk of developing breast cancer. In fact, taking estrogen alone lowers the risk for all cancers according to a report in the New England Journal of Medicine.
This is great news for women. Things have changed so much that the American College of Obstetricians and Gynecologists (ACOG) recently released an opinion piece saying that women who have estrogen receptor-positive breast cancer can discuss taking vaginal estrogen with their healthcare providers. And that is true whether they are currently being treated or a breast cancer survivor.