Does hormone replacement therapy cause breast cancer?

A jury recently awarded three women $72.6 million against Pfizer for finding PremPro as the cause of their breast cancer. This has once again placed women in and around menopause incredible stress: to take or avoid hormone replacement therapy (HRT).

It’s a difficult situation. Estrogen is very effective against hot flashes and other symptoms of menopause. But some women fear it; others are uneasy; some won’t consider stopping it. No matter how you feel about estrogen, it remains the only government approved drug therapy in the United States and Canada for treating menopause-related symptoms.

Prior to 2002 and the publishing of the Women’s Health Initiative study, a very large percentage of women in menopause were taking estrogen or estrogen plus progestin or progesterone. After the study, which showed that estrogen plus progestin caused an increased risk of breast cancer, heart attack, blood clots and stroke, many women went cold turkey and stopped everything.

I remember my phone ringing off the hook with concerned women. Half the calls were women looking for an alternative to HRT. The other half the calls were from women wanting to know if they could stay on their estrogen. Since that original study, we’ve learned a lot more about estrogen. The most important one is that estrogen therapy has to be individualized and periodically reevaluated. Here are a few things every Intent woman should know about her hormone therapy.

First, the terms:

Drugs that contain estrogen are divided into two categories:

  • ET stands for estrogen therapy. These contain estrogen only. I’ve included an important video about ET and breast cancer risk below to help you.
  • EPT stands for estrogen-progesterone therapy.
  • HT stands for hormone therapy and can refer to either ET or EPT.
  • HRT stands for hormone replacement therapy. It’s still used a lot by lay people but it isn’t currently used as much by the medical community.


Now the estrogen types:

There are four types of estrogens.

  • Human Estrogens. There are three human estrogens – estradiol, also called 17b-estradiol, is the strongest one. Estrone is 50-70 percent less active. Estriol is 10 percent as active as estradiol. Estradiol is the only government approved single-estrogen product.
  • Non-Human Estrogen. These are also called conjugated estrogens or CE. These are a mixture of at least 10 estrogens obtained from natural sources, typically, the urine of pregnant mares. Their effects are caused by the sum of the 10 or more estrogens.
  • Synthetic Estrogens. These are manufactured in chemical plants and resemble human and non-human estrogens.
  • Plant-Based Estrogens. These are also called phytoestrogens. Some act like an estrogen and others act like an anti-estrogen, depending on which part of the body the phytoestrogens affects. These are not prescription hormones. These are commonly found in foods such as soy, flaxseed, red clover and others.


The recent Pfizer jury award is sure to scare women. Whether or not to take estrogen and or progesterone is a very personal decision that needs to be individualized. Think of it as you should consider whether or not to take any other medication: it depends on your history, why you are taking it and what alternatives exist.

For those of you considering HT, I strongly suggest you have a detailed discussion with your healthcare provider that addresses your personal needs, wants and desires. It’s important to know what symptoms you are hoping to alleviate, what the risks are for you as an individual and what alternatives exist for you.

In order to help you prepare for that discussion and to help you get the most out of your visit, I’ve written an eBook on estrogen and progesterone to serve as your guide. I’m offering it free to Intent readers as a special gift. Click here for instant access and download this hormone guide eBook now.