BRCA, Hormones, and Breast Cancer: It’s Time to Change the Conversation

PerfeQTion™ Imaging & Wellness · October 5, 2026

Women with BRCA1 or BRCA2 mutations are still being told two things:

“You’re at high risk for breast cancer, so estrogen is dangerous for you.”

And:

“You’re not a candidate for hormone replacement therapy.”

But there is a problem.

The modern data do not support that blanket advice.

In fact, we now have more than 20 years of research showing that hormone replacement therapy does not appear to increase breast cancer risk in BRCA carriers who have not had breast cancer. And some of the data on estrogen alone point in exactly the opposite direction.

And yet women are still being denied hormones because of fear rather than evidence.

The newest data: 1,352 BRCA carriers

The newest major study by Kotsopoulos and colleagues was published in the 2026 Journal of the National Cancer Institute.

Researchers studied 1,352 women with BRCA1 or BRCA2 mutations — 676 HRT users matched with 676 nonusers.

After an average of 5.6 years:

• 12.9% of HRT users developed breast cancer
• 18.9% of nonusers developed breast cancer

And estrogen alone?

HR 0.37 — a 63% lower observed hazard of breast cancer.

Estrogen plus a progestogen showed no statistically significant increase in breast cancer risk with a hazard ratio of 0.94.

Does that prove estrogen prevents breast cancer? No.

But please explain to me how these data support telling BRCA mutation carriers that estrogen is inherently dangerous.

They don’t.

And this isn’t one study

We’ve been seeing the same signal for decades.

2005 — PROSE Study: 462 BRCA1/2 carriers. HRT did not negate the breast cancer risk reduction associated with prophylactic oophorectomy.

2008 — Eisen et al.: 472 postmenopausal BRCA1 carriers. HRT use was associated with 42% lower odds of breast cancer. Estrogen alone was associated with 49% lower odds.

2016 — Kotsopoulos et al.: 864 BRCA1 carriers. HRT was not associated with increased breast cancer risk: OR 0.80. And this study matters for another reason: approximately three-quarters of these women had undergone natural menopause, not surgical menopause. Their average age at enrollment was approximately 58.

2018 — Kotsopoulos et al.: 872 BRCA1 carriers after oophorectomy. Overall HRT was neutral: HR 0.97. At 10 years, cumulative breast cancer incidence was 12% with estrogen alone versus 22% with estrogen plus a progestogen.

2025/2026 — Kotsopoulos et al.: 1,352 BRCA1/2 carriers. Again, no increased risk from HRT, with a striking association between estrogen-only therapy and lower breast cancer risk.

At some point, we have to stop pretending that “BRCA mutation = no hormones” is an evidence-based statement.

It isn’t.

A BRCA is not a breast cancer diagnosis.

A BRCA mutation is a defect in DNA the repair genes that increase susceptibility to certain cancers.

Having a BRCA mutation is not the same thing as having breast cancer.

Having a BRCA mutation does not mean you are destined for breast cancer.

And it is not, by itself, a contraindication to hormone replacement therapy.

In fact, current guidelines already recognize that BRCA carriers who undergo risk-reducing removal of their ovaries before menopause should be offered HRT when there is no other contraindication.

So why are so many women still being told they aren’t candidates?

And there is another part of this conversation that bothers me even more.

Why are we telling them to stop at 50?

A young woman with BRCA may be advised to remove her ovaries years — sometimes decades — before natural menopause.

We acknowledge that premature hormone deprivation has consequences, so we graciously “allow” her to replace those hormones until approximately age 50 or 51.

And then what?

Why are we stopping?

Where is the data showing that she needs to stop?

Nothing magical happens on a woman’s 51st birthday.

Estrogen does not suddenly become carcinogenic because she has crossed the average age of natural menopause.

Age 50–51 makes sense as a minimum duration of replacement after premature ovarian loss. It does not establish a biologic expiration date for hormone therapy.

And modern menopause medicine has already moved away from arbitrary stop dates.

The Menopause Society states that hormone therapy does not need to be routinely discontinued after age 60 or 65. Duration should be individualized according to a woman’s health, symptoms, benefits and risks.

So why should a BRCA carrier automatically be treated differently?

What happens when women continue hormones?

We now have enormous general-population datasets examining exactly that question.

A 2024 Menopause study examined prescription and health records from more than 10 million Medicare women from 2007 through 2020.

Among women using estrogen alone beyond age 65, estrogen use was associated with:

19% lower all-cause mortality

16% lower breast cancer risk

as well as lower observed risks of several other significant outcomes.

The results varied by hormone, dose and route, and lower-dose, nonoral estrogen and estradiol tended to have more favorable associations.

Again: observational data.

Which brings me to one of my biggest frustrations with this entire conversation.

“But those are observational studies.”

Yes.

Observational studies cannot prove causation.

And yes, there is something called healthy-user bias: women who choose hormone therapy may already be healthier or engage in healthier behaviors.

Fair enough.

But which came first, the chicken or the egg?

We don’t know.

What I do know is that scientific caution cannot only work in one direction.

We cannot say:

“A 63% lower observed breast cancer risk doesn’t prove estrogen is protective.”

And then turn around and say:

“But we should assume estrogen is dangerous anyway.”

That’s not science. That’s dogma.

Lack of evidence is not evidence of danger.

And waiting forever for the perfect randomized trial has a cost, too.

Women are paying that cost with their life force.

It’s time for a different conversation

BRCA carriers have been caught in the vortex of estrogen fear for decades.

They are bombarded with “you shoulds.”

You should remove your breasts.

You should remove your ovaries.

You shouldn’t take hormones.

And even when hormones are offered:

You should stop them at 50.

It’s time for a new narrative.

Removing the ovaries may still provide important ovarian cancer risk reduction for appropriate BRCA carriers. But that decision should not automatically condemn a woman to decades of night sweats, brain fog, sexual dysfunction, genitourinary symptoms, bone loss, heart disease, and the other consequences of hormone deprivation.

And if we are increasingly willing to continue appropriately selected women on HRT well beyond menopause, why wouldn’t a BRCA carrier be allowed to have that same conversation?

We do not yet have a randomized trial assigning BRCA carriers at age 51 to another 30 years of hormones versus no hormones.

But the absence of that study does not prove that continuing hormones is dangerous.

What we do have is increasingly reassuring BRCA-specific evidence, postmenopausal BRCA data showing no increase in breast cancer risk, and modern menopause evidence telling us there is no arbitrary age at which hormone therapy must stop.

So perhaps the conversation with a BRCA carrier should start looking a lot more like the conversation I believe we should be having with every woman:

Here are the known risks.

Here are the potential benefits.

Here is what we know.

Here is what we don’t know.

Now, what do you want to do?

Because carrying a BRCA mutation shouldn’t take away a woman’s right to make an informed decision about her own body.

References

1. Kotsopoulos J, et al. Menopausal hormone therapy and the risk of breast cancer in women with a pathogenic variant in BRCA1 or BRCA2. J Natl Cancer Inst. 2026;118(5):856–864. Published online 2025. PMID: 41403285.
2. Rebbeck TR, et al. Effect of short-term hormone replacement therapy on breast cancer risk reduction after bilateral prophylactic oophorectomy in BRCA1 and BRCA2 mutation carriers: the PROSE Study Group. J Clin Oncol. 2005;23(31):7804–7810. PMID: 16219936.
3. Eisen A, et al. Hormone therapy and the risk of breast cancer in BRCA1 mutation carriers. J Natl Cancer Inst. 2008;100(19):1361–1367. PMID: 18812548.
4. Kotsopoulos J, et al. Hormone replacement therapy after menopause and risk of breast cancer in BRCA1 mutation carriers: a case-control study. Breast Cancer Res Treat. 2016;155(2):365–373. PMID: 26780555.
5. Kotsopoulos J, et al. Hormone Replacement Therapy After Oophorectomy and Breast Cancer Risk Among BRCA1 Mutation Carriers. JAMA Oncol. 2018;4(8):1059–1065. PMID: 29710224.
6. The North American Menopause Society Advisory Panel. The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022;29(7):767–794. PMID: 35797481.
7. Baik SH, Baye F, McDonald CJ. Use of menopausal hormone therapy beyond age 65 years and its effects on women’s health outcomes by types, routes, and doses. Menopause. 2024;31(5):363–371. PMID: 38595196.
8. American College of Obstetricians and Gynecologists. Hormone Therapy in Primary Ovarian Insufficiency. Committee Opinion No. 698.
9. Jacobson M, et al. Risk reduction strategies for BRCA1/2 hereditary ovarian cancer syndromes: a clinical practice guideline. Hered Cancer Clin Pract. 2021.