Study: Metformin may reduce risk of cancer

EAST LANSING, Mich. — A drug commonly used to treat Type 2 diabetes may reduce the risk of diabetes-associated cancers, including breast cancer, according to a new study.

The research, led by Michigan State University pediatrics professor James Trosko and colleagues from South Korea's Seoul National University, believed that cancers originated from human stem cells and that both natural and man-made chemicals enhanced the growth of breast cancer cells in particular. The researchers tested this concept by growing miniature human breast tumors, or mammospheres, which are activated a certain stem cell gene. The team found that estrogen and the chemicals caused the mammospheres to increase in numbers and size; however, the numbers and size of the mammospheres were dramatically reduced when metformin was added.

"People with Type 2 diabetes are known to be at high risk for several diabetes-associated cancers, such as breast, liver and pancreatic cancers," Trosko said. "While metformin has been shown in population studies to reduce the risk of these cancers, there was no evidence of how it worked.

"While future studies are needed to understand the exact mechanism by which metformin works to reduce the growth of breast cancers, this study reveals the need to determine if the drug might be used as a preventive drug and for individuals who have no indication of any existing cancers," he said.

The study was published in the most recent edition of PLoS One.

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