Efficacy and safety of ultra-low dose 0.005% estriol vaginal gel for the treatment of vulvovaginal atrophy in postmenopausal women with early breast cancer treated with nonsteroidal aromatase inhibitors: a phase II, randomized, double-blind, placebo-controlled trial

OBJECTIVE: To assess the efficacy and safety of ultra-low dose 0.005% estriol vaginal gel in women with breast cancer receiving nonsteroidal aromatase inhibitors (NSAIs) and experiencing treatment-related vulvovaginal symptoms and signs. METHODS: Women with hormone receptor-positive early breast cancer receiving NSAIs were randomized to either estriol vaginal gel or placebo for 12 weeks. Vaginal maturation, vaginal pH, and total and individual scores of symptoms and signs of vulvovaginal atrophy were assessed at baseline and at weeks 3 and 12; sexual functioning was also evaluated using the Female Sexual Functioning Index (FSFI) questionnaire, as well as circulating estrogens, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). RESULTS: Sixty-one women with a mean age of 59 years were included: 50 received 0.005% estriol vaginal gel and 11 received placebo. Active treatment significantly improved maturation value and pH, vaginal dryness and global scores of symptoms and signs. Active treatment also increased the total FSFI score and all the FSFI domains, with the exception of pain. Small oscillations were observed in FSH and LH, which remained within the postmenopausal range. Estriol levels increased initially and normalized by week 12, and estradiol and estrone remained mostly undetectable throughout the study. CONCLUSIONS: Ultra-low dose 0.005% estriol vaginal gel showed efficacy in improving the symptoms and signs of vulvovaginal atrophy. These results, together with minimal oscillations in hormonal levels throughout the treatment, support the use of ultra-low dose 0.005% estriol vaginal gel as a treatment option for vulvovaginal atrophy in women with breast cancer receiving NSAIs with an indication for treatment with vaginal estrogens.