The study was led by Geoffrey Girnun, PhD, and is adds to a growing body of research in the field of associations between diabetes and cancer. However, though many studies have looked at how metformin works to prevent cancer, the team led by Girnun, who is an assistant professor in the department of biochemistry and molecular biology at the University of Maryland School of Medicine, is one of the first to evaluate liver cancer.
According to Girnun, ‘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.’
The study was done using experiments on mice. Girnun and his colleagues chemically induced liver tumours in the animals. There was a control group that was given no medication, and another that was given the diabetes drug. The results were that the wellbeing of the mice who took metformin was improved dramatically, as they displayed minimal signs of tumour activity. The tumours of the control mice, on the other hand, grew significantly.
The researchers also showed why this happened. Lipid synthesis in your liver is a process that is known to promote cancer, and metformin prevented liver cancer in part by inhibiting this process. Diseases such as diabetes, obesity, hepatitis and non-alcoholic fatty liver disease are associated with increased lipid synthesis, and so it may not be a surprise that those who suffer with these conditions are at the greatest risk for liver cancer, and drugs developed for the treatment of one ailment, such as diabetes, could help to protect against consequential ones, like cancer.
However, Girnun says that the mechanism by which metformin prevents liver cancer may be transferable to these other patient populations at risk for liver cancer, even though only people with diabetes are currently prescribed metformin for their condition: ‘So we are talking about a targeted population that will receive this benefit.’ The next step in Girnun’s plan is to undertake a clinical trial in patients at risk for liver cancer. He hopes to confirm the chemopreventive qualities observed in mice will be likewise seen in humans.