Metformin linked to tumor reduction in mouse study.

New research in mice suggests that metformin, a drug widely used to treat type 2 diabetes, may guard against lung cancer.

The drug's prospects are not yet confirmed because researchers still need to test it in people. But, in mice, "this well-tolerated, FDA-approved diabetes drug was able to prevent tobacco carcinogen-induced lung tumors," Dr. Phillip A. Dennis, senior investigator in the medical oncology branch of the U.S. National Cancer Institute, said in a news release from the American Association for Cancer Research.

Dennis and colleagues treated mice with metformin for 13 weeks after exposing them to a chemical derived from nicotine. The drug reduced lung tumors by 40 percent to 50 percent when given by mouth and by 72 percent when given by injection.

Dennis said the levels of the drug given to mice would be easy to reach in humans.

The findings are slated to be presented Monday at the American Association for Cancer Research's annual meeting, in Washington D.C.