Dr Rachel Thompson is Head of Research Interpretation at World Cancer Research Fund International. She has a degree in biochemistry from the University of Leeds and a PhD in nutritional epidemiology from the University of Southampton, where she also spent 17 years involved in teaching and research.
Liver cancer has become the 10th cancer to be strongly linked with obesity, following the publication today of our report reviewing the global evidence of the links between diet, weight, physical activity and cancer.
It joins a growing list of cancers linked to weight with advanced prostate and ovarian cancer added last year. Post-menopausal breast, bowel (colorectal), pancreatic, kidney, gallbladder, womb (endometrial), liver and oesophageal (adenocarcinoma) make up the other cancers.
An important reason why more cancers are being added to the list of those associated with cancer risk, is that the research is becoming more detailed. For example, a link between weight and advanced prostate cancer, uncovered in our report last year was found because studies had analysed data for advanced prostate cancer separately from those identified through screening for the disease.
This latest review of the global evidence on liver cancer uncovered 14 new or updated studies, giving a total of 15 studies. A meta-analysis of 12 of these studies showed a statistically significant 30% increased risk of liver cancer per 5 BMI units.
Why is body fat a risk factor for cancer?
Body fatness directly affects the levels of several circulating hormones such as insulin, insulin-like growth factors and oestrogens, creating an environment that encourages the creation of cancerous cells. Body fatness is also known to stimulate the body’s inflammatory response, which may contribute to the creation and progression of several cancers. In addition, body fatness is strongly associated with an increased risk of type 2 diabetes which, in turn, is associated with increased risk of a common type of liver cancer known as hepatocellular carcinoma.
A global public health issue
With 1.9 billion adults overweight or obese worldwide this is a public health issue. About half a million cases of cancer may be attributed to excess weight. These figures are based on a recent report from the International Agency for Research on Cancer, which estimated that 481,000 cases of cancer could be prevented, based on eight cancers (not including advanced prostate and liver). After not smoking the best thing people can do is to keep a healthy weight. The reports from our Continuous Update Project (CUP) offer the most comprehensive reviews of global research into the relationship between diet, weight and physical activity and cancer. See our one minute video outlining our 10 Cancer Prevention Recommendations or follow us at twitter.com/wcrfint.