Use of Vaginal Estrogen in Breast and Gynecologic Cancer Survivors

To review the safety, efficacy, and clinical considerations of vaginal estrogen therapy for the treatment of genitourinary syndrome of menopause (GSM) in patients with a history of breast or gynecologic cancer. This is a narrative review of the current literature and clinical guidelines which evaluate vaginal estrogen use in cancer survivors, with a focus on the key outcomes of cancer recurrence and mortality as well as dosing considerations. Vaginal estrogen therapy is consistently associated with significant improvement in GSM symptoms and quality of life. There is minimal systemic absorption with low-dose formulations, with serum estradiol levels remaining within postmenopausal ranges. Large observational studies and meta-analyses show no increased risk of breast cancer recurrence or mortality among users, including those with estrogen receptor-positive disease and those on tamoxifen. Data on patients receiving aromatase inhibitors (AIs) are more limited. Current evidence supports the safety and efficacy of low-dose vaginal estrogen for GSM in most cancer survivors, with no clear increase in recurrence or mortality. Although nonhormonal therapies should be considered first-line, low-dose vaginal estrogen is an appropriate and effective option for patients with refractory symptoms along with shared decision making and multidisciplinary care. Further prospective studies are needed, especially in patients receiving AIs.