Metformin May Protect Against Liver Cancer

Metformin, a widely used, well-tolerated drug prescribed for patients with diabetes, may protect against liver cancer, according to a study published in Cancer Prevention Research, a journal of the American Association for Cancer Research.

The study, led by Geoffrey Girnun, Ph.D., an assistant professor in the department of biochemistry and molecular biology at the University of Maryland School of Medicine, is one more in an ongoing look at the effect of metformin in cancer prevention. However, it is one of the first to evaluate liver cancer.

“Since many of the effects of the drug take place in the liver, we were surprised when we reviewed the literature that there was no direct evidence for a protective effect of metformin in liver cancer except for a few retrospective epidemiological studies,” said Girnun.

He and his colleagues chemically induced liver tumors in mice. The mice taking metformin displayed minimal tumor activity, while the control mice displayed significant tumor growth.

Girnun’s team also showed that metformin prevented liver cancer in part by inhibiting lipid synthesis in the liver, a process known to promote cancer. Patients with diabetes, obese individuals, patients with hepatitis or patients with nonalcoholic fatty liver disease are at the greatest risk for liver cancer. All these diseases are associated with increased lipid synthesis. While diabetic patients are already prescribed metformin for their conditions, according to Girnun, the mechanism by which metformin prevents liver cancer may be transferable to these other patient populations at risk for liver cancer.

“So we are talking about a targeted population that will receive this benefit,” he said.

What are the Symptoms of Liver Cancer?

Most of the time liver cancer in the early stages does not cause symptoms. If symptoms are present, they may include:

- unexplained weight loss
- on-going lack of appetite
- fullness after a small meal
- a swollen liver or a mass that can be felt in the area of the liver
- ongoing stomach pain extending to the back and shoulder
- a swollen abdomen
- yellow-green color to the skin and eyes (jaundice)
- increased symptoms of illness in those who have chronic hepatitis or cirrhosis

The above symptoms could be caused by liver cancer, but they also can be caused by other cancers or conditions. It is important to report any of these symptoms to a doctor.

Girnun is currently planning a clinical trial in patients at risk for liver cancer to determine if the chemopreventive qualities observed in mice are confirmed in humans.