Hormone Therapy After Breast Cancer: Where the Research Stands in 2026

Name: Hormone Havoc
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By: Terri DeNeui, DNP, ACNP, APRN-BC

It’s October. The pink ribbons are out, and so is the question I hear in my office more than any other this month: “I’m a breast cancer survivor. Am I really never allowed to have hormones again?”

For more than twenty years, the answer most women got was a flat no. No discussion, no nuance, no options. Just hot flashes, sleepless nights, painful intimacy, brain fog, and bone loss, not to mention Alzheimer’s and cardiovascular disease risk, bone loss and joint pain- and the message that this was the price of survival.

I’ve written before about breast cancer survivors who were told they could never have hormones again, left feeling hopeless and resigned to a life of misery. I still meet those women every week. But here is the good news: the conversation is finally changing. Not because of a headline, and not because of my opinion, but because the research and the regulators are starting to catch up. Let’s walk through where things really stand in 2026, what we know, what we don’t, and how you can have a smarter conversation with your care team.

How we got here: one study, one headline, two decades of fear

In July 2002, the Women’s Health Initiative (WHI) was stopped early, and the media did what the media does. Every hormone, in every form, for every woman, got lumped under one scary umbrella. Women flushed their prescriptions, and providers stopped prescribing almost overnight. Sound familiar?

What got lost was that the WHI had two very different arms. The arm using equine estrogen plus a synthetic progestin (PremPro) showed more breast cancer. The estrogen-alone arm, in women who’d had a hysterectomy, did not. In fact, the long-term follow-up published in JAMA in 2020 found estrogen alone was linked to fewer breast cancers (HR 0.78) and fewer breast cancer deaths (HR 0.60) than placebo (Cancerworld summary of the JAMA report). WOW. That flies in the face of everything women were told for twenty years.

Now, I want to be just as honest about the survivor data, because you deserve the whole picture. In 2004, a Swedish trial called HABITS gave hormone therapy to women who had already had breast cancer, and it was stopped early. In that trial, 39 of 221 women on hormones had a recurrence or new breast cancer, compared with 17 of 221 who weren’t (ScienceDaily, HABITS follow-up). The problem with that study? They used the right estrogen, but used a synthetic progestin (not progesterone) which we KNOW from the WHI increases breast cancer risk, so of course there will be more breast cancers! Also, the progestin used in that study binds tightly to androgen receptors, and when a molecule binds to a receptor that is not intended, it BLOCKS that receptor. Why is this a problem? Because testosterone is PROTECTIVE to the breasts, we want testosterone to bind to the receptors in the breasts because they create breast homeostasis, or balance, of the hormonal stimulation of breast tissue by estradiol and progesterone. Also, progesterone (not progestin) is very breast protective. These facts are found in MANY studies, more on this point later in the blog.

What changed in 2025 and 2026

In my book, I wrote that it takes medicine 8 to 13 years to change practice after new research comes out. I’m thrilled to report that the clock finally started moving.

The black box warning came off. In November 2025, the FDA began removing the boxed warnings for breast cancer, heart disease, and dementia from menopausal hormone therapy labels. In February 2026, it approved the first six updated labels, including Prometrium (progesterone), Divigel (estradiol gel), and Estring (vaginal estradiol) (Managed Healthcare Executive).
Experts started saying “it depends” instead of “never.” In 2025, a 19-member panel of oncologists, surgeons, gynecologists, and GPs published consensus statements in Menopause on hormone therapy after breast cancer, built around informed, shared decision-making (Contemporary OB/GYN).
Survivors are finally being heard. Data presented at the 2025 San Antonio Breast Cancer Symposium found 99.7% of women with breast cancer have at least one menopausal symptom. Yet in surveys, 73% got less than 10 minutes of menopause discussion. Up to 25% stop their life-saving hormone therapy because the symptoms are so miserable (Healio).

Now, don’t mishear me. This is where I have to be straight with you. The new labels still list a history of breast cancer as a contraindication, and ASCO, the national oncology society, stated plainly that the label change does not apply to survivors of estrogen-responsive cancers (ASCO Post), a statement of which I disagree with. For example, a woman diagnosed 10 years ago who is cancer free and no longer on any treatment is a different picture than a newly diagnosed breast cancer. The answer should never be never. The door is opening, but it is not wide open, and anyone who tells you otherwise isn’t giving you the full story.

Vaginal estrogen: the strongest good news

If there is one area where the research has truly caught up, it’s here. Vaginal dryness, painful intercourse, urinary urgency, and recurrent UTIs (what we now call genitourinary syndrome of menopause, or GSM) affect an estimated 50% to 75% of women after menopause. For survivors on endocrine therapy, it can be relentless.

A 2025 meta-analysis in the American Journal of Obstetrics and Gynecology pooled 6 studies and 24,060 survivors and found vaginal estrogen was not associated with more recurrence, breast cancer deaths, or overall deaths (ObG Project summary of Beste et al.).
Absorption is tiny. Vaginal estradiol raised blood estradiol by about 7.67 pg/mL on average, staying within the normal postmenopausal range. Tablets, inserts, and rings absorb less than creams (OncoDaily summary of the 2026 JCO Oncology Practice review).
ER-positive survivors in a Danish registry of 8,461 women showed no link to recurrence over nearly 10 years (same source).
Vaginal DHEA (prasterone) improved dryness and painful sex in a 464-woman trial, with estradiol staying very low even in women on aromatase inhibitors (same source).

Systemic hormones after breast cancer: personalization, not prohibition

This is the big one, and the honest answer in 2026 is: it depends on your cancer. Like I said before, not all breast cancers are the same, and the newest thinking finally treats them that way.

As I wrote in Hormone Havoc!, I have long believed the evidence against estrogen was weaker than we were told. But I also wrote that systemic estrogen for an ER-positive survivor is not standard of care, and I don’t recommend it until the research catches up. That’s still true today. The good news is that the research is on its way: a UK trial called MENO-ABC has been proposed to finally answer this question, and more than 1,200 women have already signed up to show interest.

What about testosterone?

You know I’m passionate about testosterone. The breast is rich in androgen receptors, and testosterone has an anti-growth effect on breast tissue. Pellet studies from Dr. Rebecca Glaser and others have reported lower breast cancer rates in women on continuous testosterone. In survivors, though, the data are still limited, and it’s an open research question whether testosterone, paired with an aromatase inhibitor to block conversion to estrogen, can relieve symptoms safely. I believe it deserves serious study, and I’m encouraged that mainstream oncology is now asking the question too.

New non-hormonal help for hot flashes

For survivors who can’t or don’t want to use hormones, 2026 brings real options beyond “try an antidepressant.”

Elinzanetant (Lynkuet) works on the brain’s temperature-control center instead of the estrogen receptor. The FDA approved it in October 2025 for menopausal hot flashes. In the OASIS-4 trial of 474 women taking endocrine therapy for breast cancer, it cut hot flashes from about 11 a day by 7.8 at 12 weeks, versus 4.2 with placebo. In September 2026, the FDA granted priority review to Bayer’s application to add a new use specifically for women on endocrine therapy for HR-positive breast cancer (OncLive).

Other tools your team may discuss include certain SSRIs and SNRIs, gabapentin, and cognitive behavioral therapy for sleep and hot flashes. If you take tamoxifen, ask about drug interactions, because some antidepressants can make tamoxifen less effective. And never underestimate the basics I talk about throughout my book: gut health, estrogen metabolism, blood sugar, sleep, and strength training all shape how your body handles hormones.

The problem in my opinion with all of these recommendations? It doesn’t treat estrogen as the preventative strategy that it is. You don’t get the brain, bone, heart and breast (yes breast) protection on medications that just treat the symptoms as you do with the actual hormone.

How to have the conversation with your care team

You are your own best hormone advocate. Fewer than 30% of survivors in one survey said their care team ever brought up sexual health, so don’t wait to be asked. Bring these questions to your next appointment:

What was my tumor’s receptor status (ER, PR, HER2), and how does that change my options?
Am I on tamoxifen or an aromatase inhibitor, and how does that affect which therapies are best for me?
Have we tried non-hormonal options long enough, and what’s next if they haven’t worked?
Is low-dose vaginal estrogen or vaginal DHEA reasonable for my dryness, pain, or bladder symptoms?
What is my personal risk of recurrence, and how does that weigh against my quality of life, bones, heart, and brain?
Are there clinical trials I could join?

And please hear me on this: do not start, stop, or change any hormone therapy on your own. The best outcomes I’ve seen come when the oncologist and the hormone specialist are on the same team, talking to each other, with you at the center. If your provider won’t have the conversation at all, it’s okay to seek a second opinion from someone who will.

The bottom line

Twenty years ago, a breast cancer diagnosis came with a life sentence of hormone deprivation, no questions asked. In 2026, the answer is finally becoming what it always should have been: a conversation. Vaginal estrogen now has solid reassurance behind it. Systemic therapy is being judged case by case instead of banned outright. New non-hormonal medicines are arriving. And researchers are, at last, asking the questions women have been asking me for years.

You survived cancer. You deserve to live after it, with energy, clear thinking, strong bones, and a joyful, comfortable intimate life. Don’t settle for “there’s nothing we can do.” Keep asking. Keep advocating. The science is catching up, and so is the conversation.

This article is for education only and is not medical advice. Breast cancer survivors should make any decisions about hormone or non-hormonal therapy together with their oncology team.

Sources

FDA priority review for elinzanetant in HR+ breast cancer (OncLive)