Liver Cancer Report: Obesity and Alcohol Up Risk
March 26, 2015Obesity and drinking alcohol increase the risk for liver cancer, and coffee consumption decreases the risk, according to a new report called Diet, Nutrition, Physical Activity and Liver Cancer.
The report was released by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund’s Continuous Update Project (CUP) on March 25.
“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,” CUP panel member Stephen Hursting, PhD, MPH, commented in a press release. Dr Hursting is a researcher at the University of North Carolina at Chapel Hill.
The CUP report analyzed 34 studies on research about how lifestyle factors affect the risk for liver cancer. The studies included more than 8 million people and more than 24,600 liver cancer cases. An independent panel of international experts reviewed the results.
Liver cancer is the second most common cause of death from cancer worldwide, and rates of the disease are increasing, according to World Health Organization statistics cited in the report. Because liver cancer is usually diagnosed at an advanced stage, it is associated with a poor 5-year survival rate. The disease affects men more often than women and is more common in people living in developing countries (because of hepatitis) than those in industrialized regions.
The report found that drinking coffee “probably” protects against liver cancer. The mechanism behind coffee’s protective effect is not entirely understood. Some evidence points to compounds in coffee that may help with detoxification, antioxidant defence, DNA damage, cell apoptosis, and the expression of genes involved in inflammation.
Link With Obesity “Getting Stronger”
The analysis found “strong evidence” linking higher BMI to increased risk for liver cancer.
“The evidence on obesity and cancer is only getting stronger,” Dr Hursting emphasized in the press release.
We’re looking at a tsunami of obesity-related cancer coming. Dr Stephen Hursting
“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,” he emphasized.
Other cancers linked to being overweight include ovarian, colorectal, postmenopausal breast, advanced prostate, endometrial, esophageal, kidney, pancreatic, and gallbladder.
Body fatness increases insulinlike growth factors and estrogens, according to the report. This process stimulates inflammatory responses and creates a procarcinogenic environment. Moreover, body fatness increases the risk for type 2 diabetes, a known risk factor for liver cancer. Body fatness also increases the risk for nonalcoholic steatohepatitis, which can progress to cirrhosis and increase the risk for liver cancer.
Link With Alcohol Confirmed
The report also confirms the well-known link between alcohol consumption and liver cancer, and provides the first quantification about how much alcohol is too much, in terms of liver cancer risk.
“We now have a little more precision on the alcohol-liver cancer link,” Dr Hursting also said in the press release. “Above three drinks a day seems to dramatically impact the tumorigenic process and increase risk.”
Alcohol predisposes to cirrhosis, a risk factor for liver cancer, according to the report.
Finally, the report found “limited” though “consistent” evidence that physical activity and fish consumption could decrease the risk for liver cancer, though further research is needed.
The most common hypothesis, according to the report, explains that n-3 fatty acids found in fatty fish and fish oils ― especially the long-chain polyunsaturated fatty acids ― inhibit carcinogenesis by inhibiting eicosanoid production.
Physical activity may protect against liver cancer, the report explained, by improving insulin sensitivity and body fatness, as well as decreasing chronic inflammation and oxidative stress.
“Lifestyle factors are important contributors to the development of liver cancer, and even moderate changes in diet, alcohol consumption, and exercise can prevent it,” CUP panel member Hillel Tobias, MD, PhD, said in the press release. Dr Tobias is clinical professor in the Department of Gastroenterology at New York University Langone Medical Center and cochair of the American Liver Foundation’s National Medical Advisory Committee.
“But liver cancer can also occur because of uncontrolled forms of hepatitis, including hepatitis C, which affects millions of people worldwide,” he pointed out.
Other factors that contribute to the development of liver cancer include viral hepatitis, type 2 diabetes, cirrhosis, smoking, oral contraceptives with high doses of estrogen and progesterone, and aflatoxins.
The report was developed in partnership with the World Cancer Research Fund International Continuous Update Project (CUP) and the American Institute for Cancer Research.
Continuous Update Project. Diet, Nutrition, Physical Activity and Liver Cancer. 2015. Full text