A study may have found a culprit for increasing rates of liver cancer: obesity. The study published in the journal Cancer Research found that high body mass index (BMI) and a large waist circumference were associated with an increased risk for liver cancer. In addition, having type 2 diabetes increases the risk.
Liver cancer rates have nearly tripled since the mid-1970s. Because obesity rates have increased since then as well, researchers with the American Cancer Society wanted to see if obesity was a cause of the increased liver cancer rates. Though the association has been studied in the past, most studies were small or flawed.
In this 2016 study, researchers looked at data from 1.57 million adults enrolled in 14 different studies in the United States. Of those enrolled, 2,162 had been diagnosed with liver cancer.
Compared to having a normal BMI, being overweight was associated with a 21% increased risk of liver cancer. Being obese was associated with an 87% increased risk of liver cancer, and the more obese, the higher the risk.
BMI is a measure of body fat based on height and weight that applies to adult men and women. While not the only measure of health, experts recommend BMI scores be between 18.5 and 24.9—calculators are available online.
A BMI of 25 to 29.9 indicates a person is overweight, on this scale, and 30 or greater indicates obesity.
For every 5 kg/m2 (about 1 pound per square foot) increase in BMI, there was a 38% and 25% increase in the risk for liver cancer in men and women, respectively.
Waist circumference also increased the risk, though not as much, and type 2 diabetes was associated with more than two and a half times the risk, after accounting for other risk factors like alcohol consumption, smoking, and BMI.
The effects appeared to be compounded if people had more than one risk factor. For instance, type 2 diabetes was associated with higher risks of liver cancer at each increased level of BMI.
Liver cancer is not as common as some other cancers, and even if the risk is doubled, it remains on the low side.
“The lifetime risk of a person developing liver cancer is 1%. Having diabetes, for example, would double that risk,” says Peter Campbell, Ph.D., strategic director of Digestive System Cancer Research at the American Cancer Society.
Still, this year, an estimated 39,230 Americans will be diagnosed with liver and bile duct cancer, and about 27,170 people are expected to die of adult liver cancer, according to the National Cancer Institute.
Liver cancer has a poor prognosis, even when diagnosed at relatively early stages, so it’s important to have a better understanding of how to prevent it, the authors wrote in the study.
Experts believe that fat tissue in the liver produces inflammation, which may lead to changes in liver tissue including the development of fibrosis and cirrhosis as well as increased risk of insulin resistance. Over time, these changes may lead to liver cancer.
“This adds substantial support to liver cancer being on the list of obesity-associated cancers,” says Campbell. “Along with reducing known risks—excess alcohol consumption and hepatitis infection—maintaining a healthy body weight, eating healthy, and staying physically active to reduce the risk of diabetes may be important preventive strategies to reduce the risk of liver cancer,” he says.