Metformin intervention against ovarian toxicity during chemotherapy for early breast cancer: study protocol for a randomized double-blind placebo-controlled trial

Abstract Background With the significant improvement of the cure rate and survival rate of cancer patients, the survivors face quality-of-life problems, such as a significant decline in reproductive system development, ovarian reserves and function, and even fertility loss and early menopause. These problems are often highly associated with chemotherapy-induced ovarian damage in cancer treatment. However, there are no ideal treatment strategies at present. In our attempt to develop reagents and approaches for delaying ovarian aging and protecting chemotherapy-induced ovarian injury, we recently found that metformin may be the most promising drug to protect female malignant tumor patients from chemotherapy-induced ovarian injury. This trial aims to test whether administration of metformin during chemotherapy can protect the normal ovarian function of patients with early breast cancer. Methods This study is prospective, randomized, double-blind and placebo-controlled. Female patients with early breast cancer (N = 314) will be randomly assigned to two groups (placebo, metformin 2000 mg). Metformin will be administered during and after chemotherapy for patients with stage I-IIIa breast cancer. The primary outcome will be the menstruation recovery rate 12 months after chemotherapy, defined as recovery of menstruation twice in a row within 1 year. Patients will be followed up for 5 years to observe long-term ovarian function and prognosis, such as overall survival (OS), objective response rate (ORR), and disease-free survival (DFS). Quality of life and safety will also be assessed. Discussion Our research will provide a new treatment strategy for fertility protection, and clinical treatment guidance for cancer patients.