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  • Writer's pictureMonica Bell

Breast Cancer & HRT

Updated: Dec 16, 2021

So many women are concerned about hormone replacement therapy (HRT) and breast cancer risk.Let's get real with the data and the risks so you can make an informed decision about your health. 

A recently published research article in the Lancet states that there is an increase risk of breast cancer in women who took oestrogen and progestagen, with the greatest risk being women who took oestragen and progestagen daily for over 10 years.

I feel that some news sources didn't represent this article well. Let me give you my perspective.

Let's break this article down... 


First let's define a few terms:  Oestragen- any form of estrogen therapy. Synthetic or natural, such as Premarin or estradiol taken orally or topically.  Progestagen- any form of progesterone synthetic or natural.  Why do these terms matter? Because not all estrogens and progestins are equal in risk. Relative Risk- Relative Risk is considered a descriptive statistic, not an inferential statistic; as it does not determine statistical significance.  Relative Risk utilizes the probability of an event occurring in one group compared to the probability of an event occurring in the other group. A relative risk greater than 1 indicates a positive risk relationship.


A few notes about research:

 This article in the Lancet was an observational study. In the research world a randomized control trial is the highest level of evidence, or level 1 evidence. While there is information to be learned from a observational study it is not regarded as the highest quality evidence in the medical world. 

Also, they only mention relative risk and not if the risk was statistically significant- (which is a big deal in research) more.


What was the risk? 

According to the Lancet article the Relative risk of breast cancer on HRT for over 10 years on oestrogens and progestagens was 2.5.

Does this change my practice?

No. Why? I don't prescribe synthetic progestins. I only prescribe micronized progesterone or natural progesterone, which has not been associated with breast cancer.


The positives about the article. 

Vaginal estradiol, or we can say topical estrogen, had a decreased risk of breast cancer. 

So this has me asking myself- Does Estrogen really cause breast cancer?

We understand that article may cause some alarm, when you put it into perspective it's not so scary. For example, here are some other relative risks that have been associated with breast cancer.

Relative risk between using an electric blanket and breast cancer is


Relative risk of high consumption of carbohydrates and breast cancer is


Relative risk and being left handed and breast cancer is 


Here's a relative risk that is really meaningful- the relative risk of smoking and lung cancer is



Modifiable Risks

There are lots of lifestyle choices that actually affect our risk of breast cancer. Here are some examples:


Studies show 1-2 drinks per day increased the risk by 10%, 3 drinks increases by 30%.

Being Overweight/Obese

Studies show there is an increased risk of breast cancer with a BMI >25


Strenuous physical activity decreases breast cancer risk by 10-22%


So, How Can We Decrease our Breast Cancer Risk? -Consume high quantities and varied types of low carb vegetables -Eat organic, unprocessed, low sugar foods -Adequate exercise intake  -Low alcohol intake -Avoid tobacco -Optimize vitamin levels (D, B12) Take Home Message HRT is a personal choice. Weighing the risks and the benefits with your practitioner. This is with anything we do in life. There have been plenty of articles that show multiple benefits from HRT as well. Increase bone density, less dementia, less heart disease and lets not forget about improving our vaginal health and sex lives! As many of you have heard me say before, there are risks to not treating menopause.

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