For the first time, a report from an ongoing systematic review of global research found that obesity and three daily alcoholic drinks clearly increases risk of liver cancer, a disease that is increasing in the U.S. and the second leading cause of cancer deaths worldwide. The report also found that coffee offers protection from this disease.
Diet, Nutrition, Physical Activity and Liver Cancer was published last month by World Cancer Research Fund International, in partnership with AICR. The report also found strong evidence linking body fatness to increased risk for liver cancer. This means that liver cancer now officially joins the growing list of cancers caused by overweight and obesity.
The latest Continuous Update Project (CUP) report analyzed 34 studies involving over 8.2 million people and over 24,500 cases of liver cancer. It is the most in-depth review to date of global research linking diet, physical activity, and weight to the risk of developing liver cancer.
“The evidence on obesity and cancer is only getting stronger... We’re looking at a tsunami of obesity-related cancer coming."
A tsunami of obesity-related cancers
With today’s report, liver cancer becomes the tenth cancer to be strongly associated with overweight and obesity. Taken together, AICR estimates that in the United States, staying lean would prevent approximatley 120,000 cases of cancer a year.
“This is the first time there’s been such a clear signal from a rigorous systematic review on the links between obesity increasing risk of liver cancer and coffee decreasing risk,” said Stephen Hursting, Ph.D., M.P.H., researcher at the University of North Carolina Chapel Hill and one of the CUP expert panelists.
“The evidence on obesity and cancer is only getting stronger... We’re looking at a tsunami of obesity-related cancer coming. People really need to be aware of this issue and we need more research on weight loss strategies and understanding the mechanisms so that we can break this connection.”
There are several possible mechanisms in which excess body may promote the development of cancer, note experts. Body fat releases hormones into the bloodstream, which contribute to insulin resistance and a pro-inflammatory bodily environment that may encourage the cancer process, for example.
Alcohol Increases Risk: Coffee Decreases
The report also reaffirms the clear link between alcohol consumption and liver cancer, and for the first time quantifies the amount at which risk for liver cancer rises. “We now have a little more precision on the alcohol-liver cancer link,” said Hursting. “Getting above three drinks a day seems to dramatically impact the tumorigenic process and increase risk.”
Experts at AICR were quick to note, however, that lower levels of alcohol increase risk for other cancers, including breast and esophageal. AICR recommends women limit themselves to one drink per day and men to two drinks per day.
The new report’s finding that coffee protects against liver cancer follows a 2013 CUP report that found coffee to be protective against endometrial cancer. Coffee contains a variety of naturally occurring compounds that are currently being studied for their anti-cancer potential.
“It may act on liver enzymes that eliminate carcinogens, for example,” said Hursting. Because coffee is consumed in such a variety of ways, however, it is not yet possible to determine the amount or style of preparation that provides optimal protection.
Nearly One-Third of US Liver Cancers Preventable
Given the new findings, AICR now estimates that being at a healthy weight and avoiding alcohol could prevent almost one-third (30 percent) of U.S. liver cancers every year – approximately 10,700 cases.
"This supports what research has pointed to – that there is a link between obesity and liver cancer," says Hillel Tobias, MD, PhD, clinical professor in the Department of Gastroenterology at NYU Langone Medical Center and co-chair of the American Liver Foundation's national medical advisory committee. "Lifestyle factors are important contributors to the development of liver cancer and even moderate changes in diet, alcohol consumption and exercise can prevent it. But liver cancer can also occur because of uncontrolled forms of hepatitis, including hepatitis C, which affects millions of people worldwide.”
The CUP report also uncovers intriguing indications that both physical activity and fish consumption may decrease the risk of liver cancer, although more research is needed before any firm conclusions can be reached.
Visit the Continuous Update Project section to read the new and previous CUP reports.
Published on March 31, 2015