Impact of adjuvant metformin versus placebo on invasive disease-free survival in patients with breast cancer

In observational and preclinical studies potential beneficial effects of metformin across breast cancer subtypes have been observed. The multinational phase 3 randomized MA.32 trial evaluated addition of adjuvant metformin versus placebo to standard treatment in patients with high-risk operable breast cancer without diabetes. There was no significant improvement of invasive disease-free survival with metformin compared with placebo (visual abstract).