Metformin for Chemoprevention of Lung Cancer in Overweight or Obese Individuals at High Risk for Lung Cancer

This phase II trial determines the effect of metformin extended release on the risk for
developing lung cancer in overweight/obese patients that are at high-risk for developing lung
cancer. Metformin is widely used to treat type II diabetes and has a long history of safety
and minimal side effects. At similar dosage, the drug may have potential anti-cancer
activity. Metformin use has been associated with improved survival in patients with non-small
cell lung carcinoma, a specific type of lung cancer, and it has also been shown to enhance
immune mobilization against tumors. This trial aims to see whether metformin extended release
as a preventative treatment may lower the chance of developing lung cancer, and whether it
may help patients' immune system learn ("reprogram") to lower a certain type of immune cell
(called regulatory T cells) that are linked to tumor development.