What 4 trials say about hormone therapy after breast cancer

This week’s Livelong Woman is inspired by the stories that have come up across many conversations in our Circle community, at the Livelong Women’s Health Summit, and through emails you all send me, and especially through a collaboration with Erin Beattie, the founder of Nila. It’s about the gap for people whose HRT decision isn't just about age or years since menopause, but about cancer history.

If you’d like to stop guessing about the decisions that can help you live not just more years, but improve the years we get, I’d love to invite you to join me at the upcoming NYC Livelong Women’s Health Summit next week. I have a special discount to offer the first five readers who email me at [email protected].

By Erin Beattie, founder of Nila

September 16 marks one year since my total hysterectomy with BSO. Before that: a hormone-positive breast cancer diagnosis, six months of tamoxifen and Zoladex that suppressed my estrogen and put me in chemical menopause, a bilateral mastectomy, and reconstruction. So when the surgery confirmed stage 3 endometriosis that had gone undiagnosed for nearly twenty years, the BSO didn't start my menopause; it stacked on top of the one already underway.

What I wish someone had told me: that the fear around hormones traces back to one 2002 study, and that the scariest finding in that study didn't even show up in the estrogen-alone group. 

Menopause wasn't part of my gynecology referral; I was referred for endometriosis and an MSH2 gene flag, we did the surgery, the six-week checkup closed out that referral, and that was it. My oncologist has since released me from her roster, not because anyone dropped the ball, but because stable gets released so acute can be seen. My GP is great, and very busy. Nobody is tracking my menopause, because it was never anyone's referral to own. I drive the car. The check engine light is flashing.

So I manage it with local vaginal estrogen and the same Nila tools I built for everyone else: workouts, symptom explanations with relief, nutrition, research, and I go into every appointment with my top three symptoms ranked.

That question is the one that keeps you from disappearing.

We spoke with Amy Killen, MD, a physician who has spent more than a decade in longevity and regenerative medicine and is the author of the forthcoming book The Female Longevity Advantage, who says this is a situation that needs an honest three-way conversation between the woman, her hormone provider and her oncologist. And there is no tidy expiration date on that conversation.

A BRCA variant or a family history of breast cancer is a different story, Killen says. “Neither is a reason to avoid hormone therapy on its own.” She points to research on BRCA carriers who had their ovaries removed preventively, which has not found a higher breast cancer risk from hormone therapy at least up to the age they would have reached natural menopause. That reassurance applies to women who have not had breast cancer themselves.

So who owns the decision? “The right person is the one who will actually sit with her,” Killen says. “A menopause-literate provider who talks with her oncologist rather than around her.”

This is one of the most contested questions in women’s health, and not because the evidence is damning. It’s because there is so little of it, and what exists doesn’t line up.

Four randomized trials have tried to answer the question. One found no difference in survival but more cancers in the opposite breast. One was stopped early for more recurrences. The largest was stopped early too, but it tested tibolone, a synthetic steroid that isn’t available in the US, and it supplies most of the patients in the pooled analysis that tends to get quoted. A fourth, in women whose tumors were hormone-receptor-negative, found no difference. These results don’t represent a green light, but also aren’t the flat "no" the choice is often presented as.

“We still have a lot to learn about what the real risks are and aren’t,” Killen says, “but every woman deserves that conversation, whatever her history.”

“Vaginal estrogen is a much lower dose than systemic therapy, and it works right where you put it: the vulva, vagina, urethra and pelvic floor,” Killen says. Vaginal DHEA works the same way. A tiny amount can reach the bloodstream, but it doesn’t push estrogen levels outside the normal postmenopausal range.

A Cochrane review of 30 trials and more than 6,000 women found the different formulations (creams, rings, inserts, tablets) worked about equally well, with no difference in side effects. In women with a history of breast cancer, vaginal estrogen has not been linked to a higher risk of recurrence or of dying from breast cancer. Killen’s one caveat is for women taking an aromatase inhibitor, who she says should check in with their oncologist first.

Quite a lot, and for women with a personal breast cancer history, this is usually where treatment starts. The behavioral and lifestyle tier comes first: exercise, weight loss, quitting smoking, cognitive behavioral therapy, clinical hypnosis, and acupuncture.

If those don’t move the needle, there are non-hormonal prescriptions. Low-dose SSRIs and SNRIs, gabapentin, and oxybutynin have been used for years. Two newer drugs target the brain’s temperature switch directly: fezolinetant (Veozah) and elinzanetant (Lynkuet), which the FDA approved in October 2025.

For vaginal dryness and painful sex, moisturizers, lubricants, and pelvic floor physical therapy all help. But in Killen’s view, very few women truly can’t use local vaginal estrogen or DHEA.

Unfortunately, there's no single right answer here. “In most of medicine, a quick prescription and a short list of instructions gets the job done,” says Killen. “Menopause with a complicated history is not most of medicine.”

The decision depends on how much your symptoms are affecting your life, your own risk of recurrence, and what you're willing to trade. Until the research gets clearer, the best path is a real conversation between you, your oncologist, and your gynecologist, weighing relief against risk together.

The information provided about wellness and health is for general informational and educational purposes only. We are not licensed medical professionals, and the content here should not be considered medical advice. Talk to a doctor before trying any of these suggestions.