Slicing and dicing the estrogen data

I love it when the headlines say I am doing the right thing!  You may remember that in December one of the big headlines out of the San Antonio Breast Cancer Symposium was:

Estrogen Alone Provides Protective Effect in Breast Cancer Risk Reduction

This headline caught my attention because this subject is such a hot topic of conversation for women at high risk for breast and ovarian cancer.  We want to know what effect will replacement hormones have on our breast cancer risk if we remove our ovaries pre menopausally and choose to take either estrogen alone or estrogen plus progesterone/progestins to control our menopausal symptoms.

Interestingly, these headlines were the result not of new research but the result of a rehash of old data from the Women’s Health Initiative study.  The Women’s Health Initiative is one of the largest and longest-running studies of post menopausal women that focuses on, among other things, the breast cancer and heart disease risk.  The arm of the study that involved women taking hormone replacement therapy that included both estrogen and progestins (synthetic progesterone) was abruptly halted in 2002 because the study found that women taking the combination of estrogen and progestins had a higher incidence of heart disease, stroke, blood clots, and breast cancer.  Researchers determined that the these risks outweighed the benefits of taking the hormones.   The arm of the study that involved taking estrogen only continued for another two years.  The women in the estrogen only arm of the study all had had a prior hysterectomy.

At the time the estrogen only arm of the study was stopped the researchers determined that although the risk for breast cancer was less for women taking estrogen than for those without any hormone replacement, the risk for stokes was increased.  The more recent analysis of the breast cancer data from the women involved in this trial seems to uphold the initial finding that estrogen alone was protective for breast cancer in women who had had a hysterectomy.

Sounds good right?  Especially for those of us at high risk for breast cancer who choose BSO and hysterectomy and wonder about hormone use after our surgery.

But the devil is in the details.

And the details contain one important caveat:  the risk reduction was only seen in women without a strong family history of breast cancer and without any prior breast cancer diagnosis.  Women facing increased hereditary risk of breast cancer  are not part of the analysis at all.  Where this leaves those of us at high risk for breast cancer who are grappling with hormone use for surgical menopause is with no new information. 

Bummer.

Nonetheless existing information does give reason for optimism in this realm.  Removing the ovaries prior to menopause not only reduces ovarian cancer risk, it also dramatically cuts breast cancer risk, with most studies estimating this risk reduction as approximately 50 percent.  Moreover, studies in BRCA-positive women with no prior history of breast cancer do indicate that the risk-reduction benefit remains regardless of short-term hormone replacement  to manage menopausal symptoms.