Being overweight or obese is an important risk factor for liver cancer, according to two new research papers. Both studies suggest that maintaining a healthy weight is an essential factor in preventing liver cancer, particularly for those living with hepatitis C.

According to one paper published by Chinese researchers in the September issue of the European Journal of Cancer, in which data from 26 studies involving more than 25,000 people were reviewed, excess body weight—defined as a body mass index, or BMI, between 25 kilograms per meter squared of body surface area (kg/m2) and 29.9 kg/m2—increased the risk of liver cancer by 48 percent. Among those with obesity—defined as a BMI of 30 kg/m2 or greater—the risk was 83 percent higher.

A second paper by Chinese investigators, which also reviewed previously published study results and is available online ahead of print by the journal The Oncologist, concluded that the most pronounced risk of liver cancer was among people with BMIs of 32 kg/m2 or greater.

Both studies, which included people living with viral hepatitis infection, confirmed that excess weight was an independent risk factor for liver cancer. In other words, the risk was heightened regardless of whether or not someone had hepatitis B or hepatitis C.  And while hepatitis C further increased the risk of liver cancer in people who were overweight or obese, hepatitis B did not.

BMI can be calculated by multiplying a person’s height in inches by height in inches (e.g., 69 X 69). The sum (e.g., 4761) is then divided into the person’s weight in pounds (e.g., 170/4761). This sum (e.g., 0.036) is then multiplied by 703, which yield’s the person’s BMI:  25 mg/m2. A BMI above 30 is considered obese. 

To read the European Journal of Cancer report, click here. To read The Oncologist report, click here. Full access to both articles requires a paid subscription.