Can breast cancer survivors safely use vaginal estrogen?

Clinical takeaway: For appropriately selected breast cancer survivors with bothersome genitourinary symptoms, low-dose vaginal estrogen was not associated with worse overall or breast cancer–specific survival, supporting its consideration as part of individualized symptom management.

Fear of recurrence often limits use of vaginal estrogen for genitourinary syndrome of menopause, leaving many breast cancer survivors with undertreated symptoms that can impair quality of life.

In a retrospective SEER-Medicare Health Outcomes Survey analysis, investigators evaluated 25,874 women aged 65 years or older diagnosed with breast cancer between 2007 and 2017, including 1,053 patients (4.1%) who used vaginal estrogen after diagnosis.

Initial adjusted analyses suggested favorable outcomes among vaginal estrogen users, with approximately 51% lower overall mortality and 69% lower breast cancer–specific mortality compared with nonusers. Among the 13,706 patients with hormone receptor–positive disease, vaginal estrogen use was associated with roughly 42% lower overall mortality, while breast cancer–specific mortality also trended lower.

However, when investigators accounted for immortal time bias by modeling vaginal estrogen exposure as a time-dependent variable, these apparent survival advantages disappeared. Importantly, no increase in overall mortality or breast cancer–specific mortality was observed in either the overall cohort or the hormone receptor–positive subgroup. Similar findings were seen among patients receiving tamoxifen or aromatase inhibitors.

As the authors noted, “Vaginal estrogen use was not associated with worse overall survival or breast cancer-specific survival among older breast cancer survivors.” They added that the loss of significance in time-dependent analyses suggests the apparent benefits seen in conventional models likely reflected selection factors rather than a true protective effect.

Overall, the findings add to growing evidence that locally administered vaginal estrogen does not appear to compromise survival outcomes and may help address the substantial symptom burden of genitourinary syndrome of menopause in breast cancer survivors.

Source: Mitchel OR, et al. (2026 June 26) JCO Oncol Pract. Survival Outcomes in Breast Cancer Patients With Use of Vaginal Estrogen Therapy: A SEER Analysis