Unhealthy lifestyle responsible for 'half of cancers' (?)

Prof. Parkin is an industrious little blighter. He has taken seventeen supposed risk factors one by one and done a meta-analysis of the effects of each one. So he has a total of seventeen journal articles in the one issue of the British Journal of Cancer.

His industry did not however seem to include any critical thought. His conclusions are simply reinforcement of the conventional wisdom and he pays no heed to the elementary truth that correlation is not causation -- preferring to rely instead on the speculations of epidemiologists. He even makes significant use of heavily criticized analyses from the sensationalist WCRF -- e.g. here. Some of his conclusions may be correct but we have no means of knowing which they are. Many of the factors he identified could well in fact be social class effects

Almost half of cancers are caused by an unhealthy lifestyle that could be avoided by quitting smoking, losing weight, exercising and drinking less alcohol, the most comprehensive study of its kind has found.

Around 134,000 cancers each year are the result of a poor lifestyle, Cancer Research UK has found.

In the most wide reaching study yet conducted into the issue, it was found that 14 different lifestyle factors ranging from smoking, to lack of exercise, eating too much salt, not having babies, drinking too much and being overweight contributed to four in every ten cancers diagnosed in the UK.

The findings expose the myth that developing cancer is 'bad luck' or down to your genes, the researchers said.

Previous studies had suggested around 80,000 cancers a year could be prevented but they did not take into account occupational exposures to things like asbestos, infections that can cause cancer and sunburn as the latest research has.

In a complex set of research studies, scientists calculated how many cancers and of what type could be attributed to each of the 14 lifestyle factors. The findings were published in the British Journal of Cancer.

Smoking was the biggest factor, causing nearly one in five of all cancers.

But Harpal Kumar, chief executive of Cancer Research UK, said most people would not know that a quarter of all breast cancer cases could be prevented along with half of colorectal cancers.

He added: "Leading a healthy lifestyle doesn't guarantee that someone will not get cancer but doing so will significantly stack the odds in your favour."

Dr Kumar said tackling unhealthy lifestyle factors linked to cancer would also reduce the risk of a host of other killer diseases such as heart disease, respiratory problems, kidney disease and others.

Professor Max Parkin, a Cancer Research UK epidemiologist based at Queen Mary, University of London, and study author, 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 per cent 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 study found that alcohol was responsible for 6.4 per cent of breast cancers and almost one in ten liver cancers.

Three quarters of stomach cancers could be avoided, mostly by not smoking, eating too much salt and consuming more fruit and vegetables.

Red meat consumption led to 2.7 per cent of cancers, almost 8,500 cases. Obesity was linked to more than five per cent of cancers or almost 18000 cases, including a third of womb cancers.

Lack of breastfeeding was linked to 3.1 per cent of breast cancers and 17 per cent of ovarian cancers.

The study did not examine how many cancer deaths would be prevented with a healthier lifestyle.

Sara Hiom, director of information at Cancer Research UK, said: “We know, especially during the Christmas party season, that it is hard to watch what you eat and limit alcohol and we don’t want people to feel guilty about having a drink or indulging a bit more than usual. But it’s very important for people to understand that long term changes to their lifestyles can really reduce their cancer risk.”

The World Cancer Research Fund did a similar exercise in 2007 coming up with recommendations to individuals on how to reduce their cancer risk by eating less red meat, taking more exercise and staying slim.

Dr Rachel Thompson, Deputy Head of Science for 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 new 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."

CiarĂ¡n Devane, Chief Executive at Macmillan Cancer Support, said: "No one chooses to have cancer and it would be wrong to blame people for making wrong lifestyle choices.

"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.

"There needs to be a cultural change, so that people see physical activity as an integral part of their lives, not just a optional add-on.”

Public Health Minister Anne Milton said: "We all know that around 23,000 cases of lung cancer could be stopped each year in England if people didn't smoke.

"By making small changes we can cut our risk of serious health problems - give up smoking, watch what you drink, get more exercise and keep an eye on your weight."


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