A drug already used to treat hot flashes in menopausal women might also help slow the growth of early-stage breast cancer, according to a major clinical trial led by researchers at Northwestern University. The drug, Duavee (a combination of conjugated estrogen and bazedoxifene), was given to postmenopausal women diagnosed with ductal carcinoma in situ, or DCIS—a non-invasive form of breast cancer that can sometimes progress into a more serious, invasive disease.
In the trial, which involved 141 women, half received Duavee daily for 29 days in the lead-up to breast surgery. The other half received a placebo. When the surgical tissue was analysed, researchers found significantly less cell proliferation in the group that took Duavee. That’s a strong sign that the drug may help stop the progression of DCIS before it becomes dangerous.
What makes this particularly noteworthy is that Duavee is already approved by the FDA to treat menopause symptoms and prevent osteoporosis. So this isn’t a risky experimental treatment. It’s a medication that’s already being used by women every day—with a well-understood safety profile and known benefits for hormonal support. Now, thanks to this new study, it might offer an entirely new benefit: reducing breast cancer risk.
The findings were first reported in the journal Cancer Prevention Research.
Why this trial stands out
DCIS currently affects more than 60,000 women in the U.S. each year. While it’s not considered invasive, it still carries a risk of developing into invasive breast cancer over time, particularly in cases where the abnormal cells are highly proliferative. Standard treatments for DCIS usually involve surgery, radiation, or hormone therapy—all of which can come with substantial side effects or long-term risks.
What this study offers is something different: the possibility of using an already-approved drug to manage DCIS with less physical and emotional disruption. The women in the trial not only experienced a drop in cancer cell activity, but they also had fewer hot flashes and no drop in quality of life. According to the researchers, that’s a rare and encouraging outcome in oncology.
Dr Swati Kulkarni, the lead investigator and a breast surgeon at Northwestern, said in an interview that the key takeaway is Duavee’s ability to reduce cell proliferation in oestrogen-receptor-positive ducts. That’s a big deal, because the majority of breast cancers are fuelled by oestrogen. The drug appears to suppress that activity, all while easing menopause symptoms like night sweats, mood shifts and poor sleep.
A better alternative to existing hormone blockers?
Currently, women with a high risk of breast cancer or early-stage disease are often prescribed drugs like tamoxifen or raloxifene. These medications are effective at reducing recurrence but are also known for harsh side effects: joint pain, hot flashes, fatigue, even an increased risk of blood clots and endometrial cancer. That makes them difficult to stick with long-term.
Duavee, on the other hand, is a combination of oestrogen and bazedoxifene, a selective oestrogen receptor modulator (SERM). The bazedoxifene component acts like a shield, blocking oestrogen’s action in breast tissue while still allowing the hormone to protect bones and ease menopausal symptoms. According to Mayo Clinic, this kind of hormonal balancing act is hard to pull off—and it’s one reason Duavee could emerge as a serious alternative to existing treatments.
What makes this development even more exciting is how well the women tolerated the drug. Patients in the trial didn’t just avoid added discomfort—they actually felt better. That’s not typical when treating breast cancer or even just trying to prevent it. Usually, patients are told to put up with the side effects for the sake of long-term protection. Duavee could change that equation.
Implications for long-term cancer prevention
While this was a relatively short study—the drug was taken for just under a month—it opens the door to much larger questions. Could Duavee prevent DCIS from becoming invasive? Could it be given to women at high risk of breast cancer in the same way tamoxifen is now? These are questions researchers are keen to explore in a longer Phase 3 trial, which would look at longer treatment periods, broader populations, and recurrence rates over time.
Dr Sheheryar Kabraji, an oncologist at Roswell Park Comprehensive Cancer Center who was not involved in the trial, called the results “promising,” but urged caution. He told reporters that reductions in tumour cell growth don’t always lead to lower recurrence or mortality. Still, in the world of cancer prevention, the first step is often reducing cellular activity—and Duavee seems to do that without compromise.
In an interview with Fox News, Kulkarni said, “This is a pivotal time. If we can give women something that makes them feel better while also helping manage early breast changes, we could transform how we think about prevention.”
What happens next
The research team is already planning further trials to investigate whether longer courses of Duavee can reduce the risk of invasive breast cancer. These studies will also look at whether it could be useful in women who have not yet developed DCIS but are genetically or hormonally at higher risk.
There’s also interest in looking at how Duavee could be used post-surgery to prevent recurrence. For now, most women with DCIS undergo lumpectomy or mastectomy depending on tumour characteristics. But for those caught in the earliest stages—before things turn invasive—a drug like Duavee could eventually offer a different path.
It may also reshape how doctors approach menopause treatment. For years, women have been told to be cautious about hormone replacement therapy because of concerns about breast cancer. But drugs like Duavee suggest that not all oestrogen-containing medications are created equal. In fact, under the right conditions and combinations, they might even do more good than harm.
Why this matters right now
Breast cancer remains the most commonly diagnosed cancer among women worldwide. Early detection has helped improve outcomes, but treatment can still be invasive, costly, and life-altering. Having more options, especially ones that are easier to tolerate, means more women might actually stick with treatment plans that reduce their long-term risk.
At the same time, menopause is often under-treated, leaving many women to suffer through symptoms that affect their sleep, mood, cognition and overall wellbeing. A drug that tackles both could have an outsized impact, especially for women navigating the double stress of cancer fears and hormonal upheaval.
With larger trials on the horizon, the coming years will show whether Duavee becomes more than just a symptom management tool. But for now, it’s offering something rare in medicine: real hope, wrapped in something already familiar, already approved, and already helping women feel more like themselves.