The latest BS about the Big C

‘If you get cancer, there’s a fair chance that it’s your fault.’ That would appear to be the message (hardly an original one) of a new report produced for Cancer Research UK. But the report really tells us more about the modern world of professional health advocacy than it does about health risks.

‘Over 40 per cent of cancer due to lifestyle, says review’, declared BBC News yesterday, which ran the story as its lead item and featured it heavily on TV and radio stations. The article said ‘Nearly half of cancers diagnosed in the UK each year – over 130,000 in total – are caused by avoidable life choices including smoking, drinking and eating the wrong things, a review reveals’. Note the certainty: this is a fact that the new report ‘reveals’, not a finding that it ‘suggests’ or ‘claims’.

The lead author of the report, Professor Max Parkin of the Wolfson Institute of Preventive Medicine, told the BBC: ‘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.’ Really?

The essential idea we are being sold here is that medical experts know that certain behaviours – like smoking, drinking alcohol, eating read meat and not eating enough fruit and vegetables – increase your risk of developing cancer by a certain percentage. So, all we need to do is work out how many people would have got cancer if no one did any of those things, take that number away from the number of people who do get cancer, and the remainder is how many people that ‘unhealthy living’ is killing. Simple, right?

According to the report, If you do all the ‘right’ things – if you are a cigarette-dodging, skinny teetotaller who avoids all red meat, barely goes out in the sun (except, perhaps, to take the prescribed 30-minute sessions of exercise five times per week), gets lashings of fibre, cuts down on salt, avoids infectious diseases and ionising radiation, and so on – then you can cut your cancer risk by over 40 per cent. On that basis, you may avoid cancer but die of boredom instead.

More specifically, even in this report there’s a huge gulf between the widely acknowledged risk of smoking – which is estimated here to cause 19.4 per cent of all cancers – and other risk factors. Smoking accounts for nearly half the lifestyle risk of 43 per cent claimed in the report. The next biggest factors suggested are overweight and obesity (5.5 per cent), lack of fruit and veg (4.7 per cent), alcohol (4.0 per cent), occupation (3.7 per cent) and sunlight (3.5 per cent). No other single factor, according to the report, is responsible for more than three per cent of cancers. Some oft-quoted examples like salt (0.5 per cent) and physical exercise (one per cent) have little effect at all. Even avoiding red meat altogether would only avoid 2.5 per cent of cancers, says the report.

Moreover, there’s a lot we don’t know about the various forms of cancer and what causes them. As the on-going debate about breast-cancer screening shows, it’s by no means certain that just because you find a lump somewhere that it will eventually kill you. And while everyone agrees that being a regular smoker will increase your risk of lung cancer considerably, things get trickier with just about every other lifestyle factor. To be fair to the report authors, they do acknowledge these uncertainties to some extent – before merrily accepting other people’s guesstimates of the risks involved and carrying on with their calculations regardless.

So, far from fruit and veg being a clear-cut benefit, the article on that topic begins: ‘There is considerable controversy over the protective effect of diets rich in fruit, vegetables and fibre, and the respective roles of the different components (including micronutrients such as folate).’ That might have something to do with the fact that a variety of big studies have found little or no benefit to getting your five-a-day, including a huge trial – EPIC – which reported in March 2010.

Or how about this on the topic of dietary fibre: ‘Dietary fibre has long been thought to be associated with a reduced risk of colorectal cancer… However, analytic epidemiological studies of dietary fibre and the risk of colorectal cancer have not yielded consistent associations.’ That’s a bit of an understatement: some studies show a significant protective effect, but others show no effect at all.

What Parkin et al tend to do, on one lifestyle factor after another, is rely on a big report by the World Cancer Research Fund (WCRF) from 2007 which did a similar job of looking at a variety of lifestyle factors and their putative role in cancer. However, as Patrick Basham and John Luik noted on spiked when the WCRF report was published, the WCRF relies very heavily on epidemiological studies and such studies have inherent problems. For example, an epidemiological study might ask people what they have eaten in a particular week, then years later look at how many people died of cancer, in the hope of finding associations between particular foods and disease. Of course, what someone ate in the particular week they filled in a questionnaire might not be typical of what they ate a year later or perhaps they misremembered what they did eat, and so on. There are all sorts of potential confounding factors that could mess up the results.

There are two different problems here. The first is that the correlation between, for example, eating red meat and cancer may be so weak that we can’t really be sure that the correlation is real. It may be due to the limitations of the study’s methods. Secondly, even if the correlation is real – that people who eat red meat are more likely to get cancer – that doesn’t mean that red meat causes cancer. There may be other things about people who like red meat that mean they are more likely to get cancer. These factors may not be obvious. That’s also why the US National Cancer Institute noted in 1994, ‘in epidemiological research, [increases in risk of less than 100 per cent] are considered small and are usually difficult to interpret. Such increases may be due to chance, statistical bias, or the effects of confounding factors that are sometimes not evident.’

Apparently none of these riders matter because the important thing is the headline: lifestyle causes cancer. It reflects a mindset among researchers, medics, politicians and campaigners that assumes that it is their job to tell us how to live our lives. Dr Harpal Kumar, the chief executive of Cancer Research UK, was at pains to say yesterday that ‘this absolutely is not about blame, it’s about making people aware of what is the truth’. Perhaps Dr Kumar has been out of the country for the past 10 years, because blaming people – fat people, smokers, drinkers, and so on – for their illnesses is absolutely what it’s all about.

And the result of reports of dubious merit like yesterday’s is that they validate the idea that our health guardians should intervene in our lives to protect us from ourselves. That means tax hikes, smoking bans, the refusal of hospital treatment and many other measures. The notion that we are autonomous beings who should be free to choose how we live our own lives is under continuous assault today. It is that trend – not having a fag, eating a burger or drinking a pint – which is truly sickening.

Rob Lyons is deputy editor of spiked. His new book, Panic on a Plate: How Society Developed an Eating Disorder, is published by Societas. (Buy this book from Amazon (UK).) Read his blog here.