Landmark Cancer Report
Obesity and alcohol major risk factors for cancer

People should aim to be at the lower end of the healthy weight range and either not drink or cut down their alcohol consumption, according to a landmark report published by theWorld Cancer Research Fund (WCRF).

The WCRF report is described as the most comprehensive ever published on the link between cancer and diet, physical activity and weight. Searches at nine academic institutions across the world, for studies published since records began in the 1960s, initially found half a million – 7,000 of which were judged to be the most relevant and robust for inclusion in the report. It includes 10 recommendations from a panel of 21 world-renowned scientists that represent the most definitive and authoritative advice that has ever been available on how the general public can prevent cancer.Unicef and the World Health Organization were among the official observers of the report’s process.

A key finding of the report is that maintaining a healthy weight (a Body Mass Index of 20-25) is one of the most important means of preventing cancer. The number of types of cancer where there is convincing evidence that body fat is a cause has risen from one to six since the last WCRF report was published in 1997, including colorectal cancer and postmenopausal breast cancer.

Prof Sir Michael Marmot, Chair of the Panel, said: “We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood. This might sound difficult, but this is what the science is telling us more clearly than ever before. The fact is that putting on weight can increase your cancer risk, even if you are still within the healthy range. So the best advice for cancer prevention is to avoid weight gain, and if you are already overweight then you should aim to lose weight.”

On alcohol, the report says that the evidence that alcohol is a cause of cancer is stronger now than ever before. Since the 1997 report, additional evidence has come to light that alcoholic drinks can increase the risk of a number of cancers, including breast and colon cancer. The WCRF report says that any alcohol consumption can increase the risk of cancer, though there is also some evidence to suggest that small amounts of alcohol can help protect against heart disease. Therefore, people who choose to drink should limit their consumption of alcoholic drinks to no more than 2 drinks for men and 1 for women a day. Allowing for international differences in the alcohol content of standard drinks, this is roughly equivalent to the standard guidance in the UK that men should not exceed 4 drinks per day and women 3 drinks per day.

Other findings in thereport include:
There is convincing evidence that processed meats, including ham and bacon, increase the risk of colorectal cancer. People who consume them are advised to do so sparingly.

The evidence that red meat is a cause of colorectal cancer is stronger than ever before. People should not eat any more than 500g of red meat a week.

This figure is for cooked meat, and is the equivalent of between 700 and 750g of non-cooked meat.

In one of the first breast feeding recommendations made by a cancer prevention report, mothers are advised to breastfeed exclusively for six months and to continue with complementary breastfeeding after that. This is because of convincing evidence that breast feeding protects the mother against breast cancer and ‘probable’ evidence that it protects the child against obesity later in life.

Professor Martin Wiseman, Project Director of the Report, said: “This report is a real milestone in the fight against cancer, because its recommendations represent the most definitive advice on preventing cancer that has ever been available anywhere in the world.

“When individual studies are published, it is impossible for the public to put them into context and know how seriously they should be taking the findings. But the great thing about this report is that it does this job for them.

“If people follow our recommendations, they can be confident they are following the best advice possible based on all the scientific research done up to this point. These recommendations are not based on one study but are based on 7,000.”

Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective. World Cancer Research Fund, 2007.