Metformin is distributed to tumor tissue in breast cancer patients in vivo: A 11C-metformin PET/CT study.

This study confirms that metformin is transported into tumor tissue in women with breast cancer. This finding support that metformin may have direct anti-neoplastic effects on tumor cells in breast cancer patients. However, distribution of metformin in tumor tissue is markedly lower than in liver, an established metformin target tissue.