Effects of Vaginal Estrogen on Serum Estradiol During Aromatase Inhibitor Therapy in Breast Cancer Patients with Vulvovaginal Atrophy: a Prospective Trial

Postmenopausal patients undergoing adjuvant letrozole therapy and experiencing VVA symptoms were treated with vaginal estradiol for 12 weeks. Gynecologic examination and symptom screening were conducted at baseline and after 12 weeks. Serum E2 levels were analyzed at baseline, and at two, four, eight, and 12 weeks. E2 levels were measured using both a routine liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and a highly sensitive (hsE2-MS) LC-MS/MS method.