The majority of breast cancer survivors are diagnosed with hormone-receptive breast cancer: cancer that’s fueled by estrogen and/or progesterone. Five to 10 years of hormone-blocking drugs (tamoxifen, aromatase inhibitors) is standard treatment, in an effort to reduce recurrence risk. But a new study shows that, for certain women, taking estrogen for 5 years can actually reduce the risk of breast cancer. What’s up with that?
One of the watershed moments in breast cancer research was a December, 2006 New York Times article highlighting a just-published study indicating that rates for the most common form of breast cancer dropped precipitously between August 2002 and December 2003: a drop of 15 percent in just 16 months.
The study concluded that that drop could be tied to the fact that so many women stopped taking hormone replacement therapy (HRT) drugs rather suddenly, exactly during that time.
Why? The National Health Institutes released initial results of its massive and ongoing Women’s Health Initiative in July 2002, indicating that HRT increased breast cancer risk.
A National Cancer Institute-funded study released in 2008 reinforced those WHI findings with 6 additional years of data. This newer study, from the Fred Hutchinson Cancer Research Center in Seattle, said that HRT use for just 3 years increased a woman’s risk of some forms of breast cancer by 400%.
In other words, if you’d taken HRT for 36 months, particularly an estrogen-progestin combination, you were four times more likely to get breast cancer than women who didn’t take HRT.
So, our reaction to these studies would be – avoid HRT.
Yes, for the most part.
But as the WHI study continues, and data continues to mount, researchers are able to draw new conclusions. And one of those new conclusions flies in the face of everything we’ve come to believe about estrogen’s effect on most types of breast cancer.
Earlier this month, the online journal Lancet Oncology published new findings from the WHI. Data indicates that, for women who’d undergone menopause due to a hysterectomy, six years of estrogen-only HRT (Premarin) actually reduced their risk of breast cancer by 23% within 5 years of finishing their course of treatment. Taking Premarin also reduced this group’s risk of dying from breast cancer.
So, what does this mean for those of us dutifully taking tamoxifen or an aromastase inhibitor (e.g., Arimidex) in an effort to prevent breast cancer from returning?
By suppressing estrogen, these drugs are supposed to discourage cancer; but they also come with a full array of menopausal side effects, including debilitating hot flashes, discouraging vaginal dryness, and devastating emotional swings.
Wouldn’t it be nice if estrogen wasn’t the cancer culprit we’ve all believed it to be?
Well, it’s pretty to believe that – but don’t stop your daily pill yet.
This most recent study applies ONLY to women who’ve had a hysterectomy, and then taken Premarin to relieve menopausal symptoms. In other words, these women weren’t breast cancer survivors when they embarked on their course of HRT.