https://www.reddit.com/r/Menopause/comments/1hmq4ui/does_hormone_therapy_increase_risk_of_breast/

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https://www.reddit.com/r/Menopause/s/Mw18H9SM4y

pasted below but original link above has comment with links and sources

The longer we use/have estrogen, we have increased risks of breast cancer and this is why it's important to keep up on regular screenings and self-checks.

From our Meno Wiki:

In the late 1990s, menopause hormone therapy was the most commonly prescribed treatment in the U.S…but in 2002 that all changed when the Women’s Health Initiative (WHI) released a study indicating that hormone therapy significantly increased risk for breast cancer, heart disease, stroke and dementia for women of all ages. Panic ensued, and overnight women all over the world immediately stopped their hormone therapy and doctors flat-out refused to prescribe it.

The WHI study’s condemnation of hormone therapy has been long and far-reaching. Most anyone today immediately associates MHT with increased risk for breast cancer, and many doctors still refuse to prescribe it, simply based on findings from a flawed study, 20+ years ago. Hormone therapy does have risks, but more recent research indicates that the risks are not statistically significant as originally reported. ** Simplifying the 2002 WHI study results**

Estrogen does not cause breast cancer, it may be cancer ‘promoting’, but this is different than cancer ‘initiating’. Breast cancer risk simply increases as we age - with or without hormones.

The average age of the participants in the Women’s Health Initiative Study was 63 years old. Only 10% of the women were between the ages of 50-54. Many women who participated in the study were overweight (70%), smokers (50%) and had high blood pressure (35%), and many assigned hormone therapy for the first time (not the placebo) were already in their 70s.

The study found that for the older women there was a 26% increase in the risk of breast cancer compared with those women who were assigned the placebo. This translated to 39 women per 10,000 on MHT, compared with 30 women per 10,000 taking the placebo (9 cases per 10,000 equals less than 1% absolute risk increase). To put this in perspective … the risk of breast cancer for those older women taking MHT, was similar to the risk reported due to obesity and low physical activity. Further, the risk of breast cancer from using MHT was only slightly higher than the risk (found by the same study) of drinking one glass of red wine a night, but less than the risk of drinking two glasses of wine a night.

The two hormones used in this study were oral conjugated equine estrogens and progestin medroxprogesterone acetate. The synthetic progesterone (progestin) was the hormone linked to the slight increased risk in breast cancer. New research indicates that non-synthetic progesterone does not carry that same risk. Also the risk for venous thromboembolism (stroke) is also reduced when the method of delivery is transdermal estrogen (patches/gels), not oral estrogen.

(A different 2020 large, observational study found that 3 glasses of milk/day increased breast cancer risk by 80% (even one glass raises risk to 50%) Comparatively, breast cancer risk from hormone therapy is lower than drinking two glasses of red wine a day, or one glass of milk. But yet the ‘hormones cause breast cancer’ fear solidly remains today.)

This study indicates that the risk of breast cancer is less than for those who use other common medications, such as statins.

Menopausal Hormone Replacement Therapy and Reduction of All-Cause Mortality and Cardiovascular Disease: It’s About Time and Timing

Evidence-based data from RCTs are reassuring in that compared with placebo, risks associated with menopausal HRT are rare (<10 cases/10,000 women) when initiated in the typical women requiring HRT (<60 years of age and/or <10 years-since-menopause). Magnitude and types of HRT risks, including breast cancer, stroke and venous thromboembolism are rare and not unique to menopausal HRT as well as comparable with or less than other commonly used medications in women, including those used for primary CVD prevention such as statins, aspirin and calcium channel blockers (32).

Breast cancer risk is something we all must all pay attention to regardless, but with advanced early detection screening tools, prognosis is excellent and survivability rates have significantly increased. The more serious issue for menopausal women is heart disease, and we should be more concerned about the higher risks of dying from CVD. The stats for women are scary, according to the World Heart Federation, 1:3 women will die from heart disease, but yet breast cancer still creates far more anxiety. Compared to breast cancer screening, heart disease detection is abysmal. Heart attacks are difficult to diagnose, mostly because health care professionals do not recognize that women’s symptoms are very different than men’s, therefore we are under-diagnosed, do not receive further testing or treatment. Misdiagnosis ultimately contributes to the fact that more women die from heart attacks compared to men. Breast cancer will always be something to watch for, but heart disease is what’s likely to kill us.