'Direct link' between cancer and obesity

Being overweight and drinking too much alcohol increase an individual's risk of getting cancer, according to a major report being released later today.

The World Cancer Research Fund survey issues a stark warning about the clear links between lifestyle, diet and exercise and the risk of developing the often fatal disease.

And it states that there is a direct relation between the extent of excessive weight and alcohol intake and the likelihood of falling victim to cancer.

The survey team has not carried out new research, but has reviewed 500,000 published papers from around the world, selecting the 7,000 most relevant and distilling their findings on cancer into a single report.

Survey chair Professor Sir Michael Marmot, professor of epidemiology and public health at University College London, said he was surprised at the strength of the link it established between weight and cancer risk.

And he said there was a "very clear message" from its findings for the general population: "Firstly, as you enter adulthood, don't put on weight. Secondly, if you are already overweight, it is likely that losing weight would lower your risk."

Prof Marmot told BBC Radio 4's Today programme: "One of the surprises to me - as a relative non-cancer expert - is the importance of obesity and overweight.

"We have known about obesity and overweight in relation to cardio-vascular disease and diabetes. The idea that it is strongly linked to cancer, I think, is relatively new."

The direct link between increased weight and increased cancer risk was even stronger than that linking cigarettes with cancer, he suggested.

"With smoking, we know that if you smoke you increase your risk, but most smokers in the end don't get cancer, so it's not a one-to-one relation," he explained.

"With obesity and overweight, it is very clear and it is a graded phenomenon. The more overweight you are, the more obese you are, the higher the risk of cancer."

Prof Marmot said that the evidence of a link between alcohol and cancer had become "much firmer" over the 10 years since a similar survey was last undertaken.

"It seems pretty clear that for cancer, it is a graded phenomenon," he said, adding: "The more alcohol, the higher the risk."

But he added: "We know that a moderate amount of alcohol protects against heart disease, so there is a balance between lowering the alcohol in order to prevent cancer and not totally doing without the protective effect on heart disease."