Estradiol is a paradoxical drug.  Women who use it to reduce menopausal symptoms run an increased risk of cancer, but women who have recurrent breast cancer may be surprised when their doctors prescribe it to control their cancer.

Let’s start with the basics.  Estradiol is a form of estrogen.  Spelling counts here!  Our bodies produce three forms of estrogen: estradiol, the main estrogen in women before menopause; estrone, the main estrogen found in women after menopause; and estriol, the weakest of the main forms of estrogen.  It is easy to get confused by these similar sounding substances.  This article is about estradiol—the form of estrogen that is most prevalent in our bodies during our fertile years.

Estradiol:  Hormone Replacement Therapy

Hormone replacement therapy (HRT) has been controversial since the Women’s Health Initiative found several significant health risks, including increased breast cancers, in women who used it.  However, health risks varied according to whether the HRT was the estrogen-only form or the estrogen-plus-progestin form.  The combination form showed a definitely higher risk for breast cancer.  Studies have been less conclusive about the breast cancer risk from the estrogen-only HRT’s like estradiol.

Estradiol for menopausal symptoms can be given in pill form, a patch, a gel that is spread over the back of the arm, a vaginal cream, or a spray-on mist.  Brand names include Estrace, Femtrace, Gynodiol, Alora, Climara, Estraderm, Estradiol Patch, Menostar, Vivelle, Vivelle-Dot, Evamist, and Estrogel.

While breast cancer risk from estradiol is lower compared to HRT’s that include progestin, women who take estradiol need to be aware that they have an increased risk for uterine and ovarian cancer, strokes, and deep vein thrombosis.  In fact, the uterine cancer risk is high enough that many doctors will prescribe estradiol only for women who have previously had a hysterectomy.

Nevertheless, women with severe hot flashes and other menopausal symptoms that are affecting their daily functioning sometimes decide that they are willing to take that risk rather than continue to suffer.  Because the risk for cancer and stroke increases with longer use of HRT’s and decreases when the HRT’s are stopped, brief use of a drug like estradiol may be appropriate in some cases.  The mantra these days for HRT is the lowest helpful dose for the shortest possible time.

You may hear people promoting bio-identical hormones.  We know that the longer a woman is exposed to her own estrogen through early age of menstruation onset or late age of menopause, the higher her risk for breast cancer. If a woman’s own natural hormones put her at risk for breast cancer, women considering bio-identical hormones need to beware. 

Many herbal supplements claim to offer a safe source of hormones, but if a supplement is strong enough to relieve menopausal symptoms, it may also be strong enough to cause health issues.