Abstract PO4-27-04: GRACE-trial: A randomized active-controlled trial for vulvovaginal atrophy in breast cancer patients on endocrine therapy

Abstract Background: Breast cancer is the most common cancer type in women worldwide. Due to hormone receptor positivity in the majority of the breast cancer tumors is endocrine therapy a crucial part in the treatment landscape of breast cancer. Selective estrogen-receptor modulators or aromatase inhibitors are the used treatment options for endocrine therapy. These medicines generate a hypoestrogenic environment by reducing circulating estrogen or by altering the effect of estrogen on tissue cells by receptor blockade. As a common side effect, vulvovaginal atrophy occurs in a majority of breast cancer patients using endocrine therapy. Vulvovaginal atrophy has a significant impact on physical and psychological wellbeing due to negative influence on quality-of-life, self-esteem and sexuality. As a consequence, adherence of endocrine therapy for the standard duration of 5 to 10 years is challenging, resulting in higher rates of therapy interruption, leading to poorer prognosis with shorter distant disease free survival. The standard treatment for vulvovaginal atrophy in postmenopausal women is based on the use of local hormonal treatment. However, when a patient has a history of breast cancer, delay of treatment and undertreatment are ubiquitous. Methods & design: In this first ever prospective randomized trial breast cancer patients on endocrine therapy with vulvovaginal atrophy will be treated with the available local treatment modalities with a 1:1:1:1 randomization: estrogen, dehydroepiandrosterone, moisturizers and a co-treatment of estrogen and probiotics. Patient-reported outcomes measurements will be implemented to investigate the efficacy of the implemented treatments. These outcome measures include symptom evaluation, impact on quality-of-life and sexuality. Safety of the treatments will be evaluated by assessing systemic sex hormones concentrations. Previous research indicated no increased recurrence risk, yet no randomized trials comparing the different modalities have been published. Primary objectives: Two primary objectives have been determined. Firstly, the efficacy of the different treatment modalities will be assessed. The assessment will be based on patient-reported outcome measurements (PROMs) and clinical evaluations such as vaginal pH and the vaginal maturation index, the latter a direct microscopic evaluation of the vaginal epithelium. Secondly, safety of the different groups will be assessed. Evaluation will be done be measuring sex hormone concentrations systemically, which will be a surrogate for safety evaluation. Secondary objectives: The secondary objective in this study is the identification of microbial alterations after treatment initiation. Identification of these alterations can help in further understanding of the pathophysiology of vulvovaginal atrophy and potentially create opportunities for new treatment strategies towards vulvovaginal atrophy in breast cancer patients on endocrine therapy. Registration: The current study is registered at the European Union Clinical Trials Register (EudraCT number 2021-001921-31). Trial status: Recruitment for the study was commenced in May 2022. At time of manuscript submission, patient recruitment was ongoing. Citation Format: Glenn Vergauwen, Piet Cools, Hannelore Denys, Tom Fiers, Koen van de Vijver, Liv Veldeman, Hans Verstraelen. GRACE-trial: A randomized active-controlled trial for vulvovaginal atrophy in breast cancer patients on endocrine therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-27-04.