Metformin Use and Breast Cancer Outcomes in Women with Type 2 Diabetes: A Policy Brief

Abstract

Background and Objectives: Breast cancer is the most common malignancy among women in Iran, and type 2 diabetes mellitus (T2DM) is a growing health challenge and a major comorbidity in these patients. Metformin, the first-line drug for diabetes management, has additional potential anticancer properties, in addition to its metabolic effects. Methods: This policy brief summarizes the evidence from a retrospective study conducted in Qazvin, Iran, on 104 patients with T2DM and breast cancer between 2019 and 2023, evaluating the association between metformin use and clinical and pathological outcomes in patients with T2DM and breast cancer. Results: The findings indicate that metformin use is associated with an earlier disease stage at presentation, lower lymph node involvement, and improved treatment response and prognosis. However, no significant associations were observed with hormone receptor status, recurrence, or metastasis. Conclusions: These findings suggest that metformin may be repurposed to improve the prognosis of patients with T2DM and breast cancer. It is recommended that health policymakers support prospective cohort studies and develop clinical guidelines to consider metformin as part of the treatment protocol for these patients.