Cancers could be prevented by lifestyle changes in over 40% of cases: study

What causes cancer? New research from Cancer Research UK shows that 40% of cancers in women and 45% in men could be prevented by a healthier lifestyle. The report found more than 100,000 cancers each year in the UK are caused by four lifestyle factors - smoking, unhealthy diets, alcohol and people being too fat.

This rises to around 134,000 cases a year when 14 lifestyle and environmental factors are taken into account. Cancer Research UK, which funded the work, says that around 134,000 people could be spared a cancer diagnosis if they took more care of themselves.

• Smoking accounts for 23% of all cancers in men and 15.6% in women. As well as lung cancer, it is implicated in other forms of the disease including bladder, kidney, pancreatic and cervical cancer.

• One in 25 cancers is linked to a person's job, such as being exposed to chemicals or asbestos, while one in 33 is linked to infections, such as the human papillomavirus (HPV), which causes most cases of cervical cancer.

• 34% of cancers in 2010 (106,845) were linked to smoking, diet, drinking alcohol and excess weight.

• In men, 6.1% (9,600) of cancer cases were linked to a lack of fruit and vegetables, 4.9% (7,800) to occupation, 4.6% (7,300) to alcohol, 4.1% (6,500) to overweight and obesity and 3.5% (5,500) to excessive sun exposure and sunbeds.

• In women, 6.9% (10,800) were linked to overweight and obesity, 3.7% (5,800) to infections such as HPV, 3.6% (5,600) to excessive sun exposure and sunbeds, 3.4% (5,300) to lack of fruit and vegetables and 3.3% (5,100) to alcohol.

Although the biggest risk factor by far is smoking, which caused 23% of cancers in men and 15.6% in women, there were also some surprises. Putting on too much weight, for instance, was found to be a greater risk for breast cancer in women than drinking alcohol, and diet accounted for 9.2% of all cancers if a lack of fruit and vegetables, too much salt and red meat and too little fibre were all included.

Obesity and being overweight were a cause of 5.5% of cancers overall – but rose to 6.9% (10,800 cancer cases) in women compared to 4.1% in men (6,500 cases). The reason for the difference is mostly breast cancer – in post-menopausal breast cancer, being overweight is a factor in 80% of cases.

Alcohol was implicated in 4% of cancers overall (4.6% in men and 3.3% in women). Too much sunbathing and the use of sunbeds caused 3.5% of cancers.

Men had a higher risk of cancer as a result of failing to eat the recommended five portions a day of fruit and vegetables – in men this was a risk factor in 6.1% of cancers, where in women it dropped to 3.4%.

The study is published in the British Journal of Cancer. Prof Max Parkin, a Cancer Research UK epidemiologist based at Queen Mary, University of London, said: "Many people believe cancer is down to fate or 'in the genes' and that it is the luck of the draw whether they get it. Looking at all the evidence, it's clear that around 40% of all cancers are caused by things we mostly have the power to change.

"We didn't expect to find that eating fruit and vegetables would prove to be so important in protecting men against cancer. And among women we didn't expect being overweight to have a greater effect than alcohol."

The other risk factors the study examined were infections such as human papillomavirus (HPV) which causes cervical cancer, occupations such as working with asbestos, lack of physical exercise, radiation, lack of breast feeding and using hormone replacement therapy (HRT).

Ciarán Devane, chief executive at Macmillan Cancer Support, said healthy lifestyle messages were not getting through. "No one chooses to have cancer and it would be wrong to blame people for making wrong lifestyle choices," he said.

"For a long time, people have been told that eating healthily, not smoking and exercising regularly can benefit them, and these figures show again the impact a healthy lifestyle can have. Yet these healthy lifestyle messages are clearly not reaching enough people. They also need to be made more relatable to people's everyday lives.

"We know that being physically active reduces recurrence rates of cancer too, as well as your chance of getting it in the first place. There needs to be a cultural change, so that people see physical activity as an integral part of their lives, not just an optional add-on."

Dr Rachel Thompson, deputy head of science for the World Cancer Research Fund, said: "This adds to the now overwhelmingly strong evidence that our cancer risk is affected by our lifestyles.

"We hope this study helps to raise awareness of the fact that cancer is not simply a question of fate and that people can make changes today that can reduce their risk of developing cancer in the future."

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