Obesity and alcohol identified as 'major factors' in cancer

The conclusion was spelled out in a report looking at a decade of evidence on links between diet and cancer.

Experts found that the only diet-related factors that definitely affected cancer risk were obesity and alcohol, but tobacco remained the single biggest cause of cancer.

Prof Tim Key, from Oxford University, said: "Fruit and vegetables are an important part of a healthy diet and a good source of nutrients. But so far the data does not prove that eating increased amounts of fruit and vegetables offers much protection against cancer.

"But there's strong scientific evidence to show that, after smoking, being overweight and alcohol are two of the biggest cancer risks."

Higher levels of certain hormones in overweight women could contribute to breast cancer, he said.

Being overweight could also increase the risk of other common cancers such as those affecting the bowel, and more aggressive forms of pancreatic, gullet and kidney cancer.

When alcohol is broken down by the body, it produces a chemical that can damage cells, raising the risk of mouth, throat, breast, bowel and liver cancers, said Prof Key.

In the UK, 15,000 cases of cancer a year were caused by alcohol and 19,000 caused by being overweight or obese.

The findings are published in the British Journal of Cancer.

Sara Hiom, director of health information at the charity Cancer Research UK, which owns the journal, said: "Too few people know about the significant cancer risks associated with obesity and drinking too much alcohol."