Is Vaginal Estrogen Use Safe in Patients With Breast Cancer?

The safety of local estrogen used to treat menopausal symptoms in postmenopausal patients diagnosed with breast cancer has long been debated. A recent large study found that local vaginal estrogen use did not adversely affect survival in patients with breast cancer and might even improve survival rates.

Importance and Rationale of the Study

Patients diagnosed with hormone receptor-positive breast cancer generally receive antihormonal therapies and experience menopause-like side effects from these treatments. Joint pain, fatigue and urinary symptoms can substantially reduce quality of life. Traditionally, nonhormonal treatments are preferred first, and local estrogen is considered only when other methods fail.

The American College of Obstetricians and Gynecologists (ACOG) also considers systemic estrogen contraindicated / inappropriate in patients with a history of breast cancer because it may increase the risk of cancer recurrence. However, there is no clear evidence that local vaginal hormone use increases this risk.

Study Scope and Methods

Olivia Mitchel and colleagues at the University of Arizona College of Medicine analyzed data from the US SEER cancer registry and the Medicare Health Outcomes Survey (MHOS) to examine the effects of local vaginal estrogen use in women aged 65 and older diagnosed with breast cancer. A total of 18620 patients diagnosed between 2010-2017 were evaluated, of whom 800 were found to use local vaginal estrogen.

This new study was presented at the 2025 ASCO Annual Meetingas Poster Abstract No: 578 .

Key Findings and Statistical Results

The analyses produced notable findings:

• Compared with women who did not use local vaginal estrogen, users had 44% higher overall survival (HR: 0.56; p<0.0001).

• A 47% improvement in breast cancer-specific survival was also observed (HR: 0.53; p=0.014).

• Survival rates increased more markedly in women who had used vaginal estrogen for more than 7 years (HR: 0.01; p<0.0001).

• Similar findings were observed in the hormone receptor-positive breast cancer subgroup (HR: 0.62; p=0.0007).

Implications for Clinical Practice

Lead author Olivia Mitchel said, “For many years, the approach was that hormonal treatments should not be used under any circumstances. However, these results support local estrogen as a safe option for improving patients' quality of life. These findings could change clinical practice and improve quality of life for many women.”

Study Limitations

Because the study results are limited to postmenopausal age groups, they are difficult to generalize to younger patients. The safety effects of different local estrogen doses were also not evaluated, and further research is needed.

Conclusion and Recommendations

The current findings indicate that local vaginal estrogen does not negatively affect survival in postmenopausal patients with breast cancer. These results may warrant reconsideration of the current treatment approach for patients with breast cancer. However, assessment should always be individualized, and decisions should be made jointly with the physician.

Integrating these findings into clinical practice could mark the start of a new era that prioritizes quality of life in breast cancer care.