Professor Tim Key

Cancer Epidemiology Unit
University of Oxford
Oxford

How does your diet affect your cancer risk?

Professor Tim Key is untangling the many lifestyle factors that affect a person’s risk of cancer, focusing mainly on diet and hormones. He is one of the leading UK researchers on the European Prospective Investigation of Cancer (EPIC), the largest study of diet and health ever undertaken. Professor Key is based at the Cancer Epidemiology Unit in Oxford, and his work is highlighting possible ways to prevent cancer and identify those who are most at risk.

EPIC by name, epic by nature

The EPIC study is following more than 500,000 people in Europe, including 90,000 people in the UK. Professor Key is overseeing a group of 60,000 participants from around the UK.

Because our diet has so many components, it’s very difficult to pin down which types of food can affect the risk of cancer. The researchers are following each person’s eating and lifestyle habits over many years and recording which participants develop cancer. They are using this data to unravel the links between diet, lifestyle and cancer risk.

For example, Professor Key has already published research from the EPIC study showing that that people who drink a pint of beer or a large glass of wine a day increase their risk of bowel cancer by about 10 per cent. Other results have shown that, overall, vegetarians are about 12 per cent less likely to develop cancer than meat eaters.

Professor Key recently reviewed a decade of studies on diet and cancer, showing that there is only weak evidence that eating large amounts of fruit and vegetables could help to protect against the disease. Studies have found that fruit and vegetables are associated with a lower risk of cancers of the mouth, foodpipe and stomach. However, these cancers are largely caused by smoking and alcohol, and it could just be that people who avoid fruit and vegetables are more likely to smoke and drink.

While there are other benefits to eating plenty of fruit and vegetables, the only diet-related factors that definitely affect cancer risk are alcohol and obesity. According to Professor Key, 'there’s strong scientific evidence to show that, after smoking, being overweight and alcohol are two of the biggest cancer risks.'

Hormones and cancer

Professor Key is also investigating how hormones affect a person’s risk of cancer. His work has shown that women with higher levels of oestradiol (a form of oestrogen) in their bloodstream have a higher risk of breast cancer. High levels of the hormone IGF-1 have the same effect, and also increase the risk of prostate cancer in men.

Professor Key’s research will help to piece together how the many different diet and lifestyle factors work together to influence a person’s risk of cancer. His work will reveal valuable information about how people can reduce their risk of cancer, ultimately helping to save more lives.