A medication widely used to treat type II diabetes may help prevent liver cancer, according to a report published in the April 2012 issue of Cancer Prevention Research. The new research demonstrates that mice prone to liver cancer treated with Glucophage (metformin) had significantly smaller and fewer tumors than those not receiving the drug. The findings could potentially pave the way for more extensive safety and efficacy testing in people at risk for the often fatal liver disease, including people living with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection.

“Based on these findings,” said Geoffrey Girnun, PhD, of the University of Maryland and a contributing author of the paper in an accompanying news release, “we believe metformin should be evaluated as a preventive agent in people who are at high risk. Many patients with diabetes already are taking this medication, with few side effects.”

Patients with type II diabetes have a two- to three-fold increased relative risk of developing primary liver cancer, the authors noted. Also at risk are people who are obese, have hepatitis or non-alcoholic fatty liver disease (NAFLD). Metformin, which is derived from the French lilac, is used to treat NAFLD as well as diabetes, and currently is being studied in connection with the prevention of a variety of cancers.

The animal study reported by Girnun and his colleagues is the first to focus on metformin and liver cancer.

“There have been several retrospective epidemiological studies linking metformin with reduced risk of liver cancer, but our study is the first to formally test whether metformin can protect against carcinogenesis—not just tumor growth and development, but actual tumor formation in the liver,” Girnun noted.

Glucose is converted into fatty acids in the liver through a process called lipogenesis. This process is increased in people who have diabetes, HBV, HCV, fatty liver disease and cancer. Girnun said that metformin reduces the level of glucose and inhibits this fatty acid synthesis.

“When you block this process, you prevent the cells from making more building blocks to make more cells. There is also no energy to put the building blocks together, and the cells are not able to proliferate, thereby preventing tumors from developing,” he explained.

In the study, Girnun and his colleagues found that mice treated with metformin in their food developed 57 percent fewer liver tumors than the mice that did not receive the drug; in addition, the size of the tumors was reduced by about 37 percent.

“Hepatocellular carcinoma represents a serious public health threat worldwide,” said E. Albert Reece, MD, PhD, dean of the University of Maryland School of Medicine. “Hepatocellular carcinoma represents a serious public health threat worldwide. With the alarming increases in obesity, type II diabetes and hepatitis B and C, an even greater number of people will be at risk of developing this cancer in the future. Not only do we need to find more effective treatments, we must also find ways to prevent it. This study conducted by Dr. Girnun and his colleagues is an excellent first step that may ultimately help us to prevent liver cancer in targeted populations.”