The World Cancer Research Fund and the American Institute for Cancer Research have just published a major report on the risk of cancer and what we can do about it. There's good news and bad news. The good news is that most of the risk of cancer is due to lifestyle factors that we can change. The bad news is that we don't want to change our lifestyle, or at least have difficulty doing so!

The Report is certainly impressive. It runs to 537 pages, including 96 pages of references to some 7,000 sources. It looks good too! The Report is a statement of the current expert opinion on how the occurence of cancer is related to nutrition and exercise. Much of what it says is not new. It's basically an update of a similar report published 10 years ago.

What's new? A simple summary of the message seems to be: eat a balanced diet, maintain a slim body and take plenty of physical exercise. There's less emphasis on eating or avoiding particular types of food. The recommended 5 servings of fruit and veg are still there but as part of a balanced diet rather than any particular antidote to cancer. The most striking connection is between meat eating and bowel cancer. The experts recommend eating no more than 500g of red meat per week and completely avoiding processed meat! The definition of processed meat is not clear but it certainly includes bacon and ham.

Risk Communication

The Report is undoubtedly a huge achievement in international scientific collaboration. However, as an exercise in the communication of risk, it is perhaps less of a success. Despite its attractive layout, the report is somewhat impenetrable once you dare to venture beyond the summary recommendations. I tried to investigate the figures behind the headlines for red meat and alcohol consumption. I was confronted with so-called forest plots showing relative risks based on different units. For example, the forest plot that shows the risk of cancer of the oesophagus from drinking alcohol is based on 1 drink per week, whereas the corresponding forest plot for bowel cancer is based on 1 drink per day. So, it's not easy to compare one with another or, more importantly, to convert the results to correspond to my own level of alcohol consumption.

The Report has been given a mixed reception by the world's media. As might be expected, it has been largely welcomed by cancer researchers and criticized by the meat lobby. A British cancer specialist said the report was too severe and Mark Lawson wrote in The Guardian, "This odd world in which everything we do is killing us quickly but everyone is living longer can only encourage a bemused and fatalistic shrug."

Perhaps the panel of experts has tried to be too ambitious, on the one hand creating a definitive scientific document on a global scale and on the other hand attempting to give risk advice to individuals. The different communication messages almost certainly require diffferent approaches and means of communication.

The Report

Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective