New Research: Duavee's Emerging Role in Breast Cancer Risk Reduction

For many women, managing menopause can feel like balancing bothersome symptoms with concerns about long-term health risks—especially breast cancer. One of the most misunderstood areas is the relationship between menopause hormone therapy (MHT) and breast cancer. Much of the fear surrounding hormone therapy stems from early misinterpretations of the Women's Health Initiative (WHI) study. Although the WHI raised valid concerns, later analysis has shown that risks were often overstated and do not apply equally to all women or all forms of MHT. Notably, the WHI’s estrogen-only arm (specifically conjugated equine estrogens, or CEE) was associated with a reduction in both breast cancer incidence and mortality.

The Promise of Duavee®

Duavee, which is a combination of CEE (Premarin) and bazedoxifene—has been FDA-approved to relieve menopausal symptoms and prevent osteoporosis. Now, new research suggests it may offer an added benefit for women concerned about breast cancer risk.

A phase 2 clinical trial examined Duavee's effects in 141 postmenopausal women diagnosed with ductal carcinoma in situ (DCIS), a non-invasive condition that can potentially progress to invasive breast cancer. DCIS accounts for 20-25% of new breast cancer diagnoses, with approximately 60,000 U.S. women diagnosed annually. Other non-invasive or pre-invasive breast conditions, including atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS), are also fairly common and increase future breast cancer risk.

Participants in the study were randomized to receive Duavee or a placebo for about four weeks before their scheduled breast surgery. This timing allowed researchers to directly examine changes in breast tissue. Women taking Duavee showed a significantly greater reduction in Ki-67, which is a protein marker of cell proliferation and cancer progression, compared to placebo.

The Science Behind Duavee

The scientific rationale centers on how hormones interact with breast tissue. Estrogens promote cellular proliferation, while selective estrogen receptor modulators (SERMs) like bazedoxifene are designed to block estrogen’s activity in breast tissue while preserving its beneficial effects elsewhere, such as bone health and vasomotor symptom relief. By combining CEE and bazedoxifene, Duavee creates a nuanced hormonal environment that reduces markers linked to malignant transformation without compromising symptom control.

Duavee belongs to a newer category of menopause treatments called tissue-selective estrogen complexes (TSECs), which combine estrogen with a SERM to tailor estrogen activity to specific tissues. CEE’s complex mix of over 50 estrogen compounds—some acting as estrogens, others as SERMs—may partly explain its unique safety profile seen in studies like the WHI.

Importantly, Duavee was well-tolerated in this study, avoiding many side effects commonly seen with other breast cancer prevention medications like tamoxifen and aromatase inhibitors, which can cause hot flashes, joint pain, and blood clots.

How Duavee Fits Into Breast Cancer Risk Management

Women with a history of non-invasive breast cancer often face limited options for managing menopausal symptoms due to concerns about traditional MHT. Duavee may offer a valuable alternative by relieving symptoms while simultaneously addressing breast tissue proliferation risk., and potentially even reducing breast cancer risk.

Although tamoxifen and raloxifene remain established options for breast cancer prevention, their side effects can limit long-term use. Duavee offers a better balance for some women, particularly those who are also seeking relief from menopausal symptoms.

The Current Limitations and the Path Ahead

The PROMISE study offers encouraging biomarker data, but it was short-term and does not yet provide information on actual long-term breast cancer outcomes. Larger, longer studies will be necessary to fully establish Duavee's role in breast cancer prevention. Still, the study supports what many experts have hypothesized based on Duavee's mechanism of action and early data.

Empowering Your Menopause Journey

Every woman’s experience with menopause is unique. Treatment decisions should consider your personal health history, risk factors, and quality of life priorities. The expanding research into options like Duavee offers hope for women who previously had few safe and effective choices.

If you’re experiencing menopausal symptoms and have concerns about breast cancer risk, discuss these new developments with your healthcare provider. Duavee may be an option worth considering as part of an individualized, evidence-informed care plan.

The Bottom Line

Science continues to evolve, offering new solutions to support women through menopause. Duavee may represent an exciting step forward—offering both effective symptom management and the potential for added breast cancer protection. As always, thoughtful conversations with your healthcare team remain key to making the best decisions for your health.