CLEAR-B: Cancer Landscape - Early Adjuvant Retrospective Registry - Breast Cancer

The treatment landscape concerning the adjuvant endocrine therapy in premenopausal patients with early-stage hormone receptor positive (HRpos) breast cancer is quite heterogeneous and therapy recommendations can vary. Tamoxifen (TAM) is a common treatment option that does not require OFS, but research suggests that adding OFS to tamoxifen may improve outcomes. Aromatase inhibitors (AI) are another option, but they can only be used with OFS for premenopausal patients. Studies have shown that AI + OFS improves disease-free survival compared to TAM + OFS, but it may lead to additional side effects such as osteopenia and bone fractures. The CLEAR-B study aims to provide a detailed description of the therapy landscape in this therapeutic setting, including recurrence rates and overall survival with AI compared to TAM, as well as a comparison of the chosen therapies within prognostic subgroups. CLEAR-B is a retrospective cohort study, collecting data of premenopausal patients who were diagnosed with early-stage breast cancer between January 2016 and June 2019 in a certified breast cancer center. These patients had an intermediate or high risk of cancer recurrence, as defined by (neo)adjuvant chemotherapy, and/or pT≥2cm at the timepoint of definitive surgery and/or at least one positive lymph node at the time of definite surgery (pN+). The primary objective is to compare the invasive disease-free survival (iDFS) of patients who were treated with AI + OFS vs. those who were treated with TAM ± OFS. Additionally, the study will compare distant disease-free survival (DDFS) and overall survival (OS) between the two groups and perform subgroup analyses according to risk stratification (stage II and III). This study will be conducted at around 75 certified breast cancer centers and will enroll up to 3000 patients.