Still no cure for cancer hysteria

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• 
• • Ben Goldacre
  • The Guardian,
  • Saturday July 19, 2008
  • Article history

The newspapers are so profoundly overrun with pseudoscience about food that there's no point in documenting it any longer.

They will continue with their Sisyphean task of dividing all the inanimate objects in the world into the ones that either cause or cure cancer, and I will sit at the sidelines, making that joke over and over again.

This week, however, the Telegraph, which has lost its science editor and its science correspondent in two months, deserves special attention, because two of its food stories went beyond stupid, and managed to give actively harmful information.

We'll start off with "Red wine could help prevent breast cancer". In fact it's even better than that. "Laboratory tests have shown that a chemical found in the skin of grapes could halt the development of most cases of the disease."

The story follows a standard template which they clearly now teach as valid in all journalism schools: a food contains a chemical, the chemical does something in a dish on a lab bench, therefore the food kills cancer in people. Or rather, red wine contains resveratrol: this chemical has been found to increase the activity of an enzyme called quinone reductase, which converts a derivative of oestrogen back to oestrogen, and that derivative can damage DNA, and damaging DNA causes mutations, and mutations cause cancer, so therefore, in the world of journalists, red wine prevents breast cancer in people.

This is a phenomena we might call "data mist": where someone gets one piece of research information lodged in their imagination and suddenly, for them, it explains the entirety of medicine.

Back in the real world there is the wine, and a whole human body. Red wine has a lot of stuff in it, including alcohol which, notably, is broken down into a chemical called acetaldehyde, and that itself causes DNA damage. Is there reason to think this might cause cancer, or would I be over-extrapolating myself?

Well. A huge number of observational studies have now been performed in real living humans, finding that people who drink more have more breast cancer. They have included careful analyses, in which they try to account perhaps imperfectly for other possible explanations for this relationship. These studies have even been collected together in a systematic review, and a meta-analysis, where all the figures are run onto one big spreadsheet, and they estimate that overall, half a glass of red wine a day increases your risk of breast cancer by 10%. If their figures are correct, alcohol causes about 6% of all breast cancer in the UK, meaning 2,500 cases a year.

So red wine, despite whatever it says on that press release you are holding in your hand, Kate Devlin, medical correspondent, does not prevent breast cancer.

Meanwhile they had "nutritional therapist Julia Fitzgerald" cheerfully informing Telegraph readers that "during the first four weeks of pregnancy taking a folic acid supplement (400 micrograms per day) can help prevent neural tube defects in the foetus such as spina bifida". You will remember that "nutritional therapist" is a term we can all legally use to describe ourselves, alongside "dilettante" "handsome" and "clown". Perhaps Fitzgerald's training in the field of "nutritional therapy" might have caused some confusion here, since folic acid for pregnant mothers is a rarity in their domain, being an intervention with an evidence base.

Sadly for Fitzgerald the evidence is not in her favour. And as all of the random women in their 30s I have asked today already knew, both Department of Health and NHS guidelines are identical, recommending very clearly that potential mothers should take a 400-microgram supplement from the time that they start trying for a baby, or from when contraception is stopped, up to and including the 12th week of pregnancy.

Perhaps Fitzgerald knows better. Perhaps she can also tell you the day you get fertilised. Perhaps this is the first time a nutritional therapist has ever recommended too few pills. And perhaps she will want to clarify her advice to 800,000 readers and their families which will increase their risk of delivering a baby with severe and disabling neural tube defects.

I will now go back to ignoring the nutritionists.

· Please send your bad science to ben@badscience.net

Why reading should not be believing

All comments (9)

• 
• • Ben Goldacre
  • The Guardian,
  • Saturday June 21, 2008

The best thing about this job is you have an excuse to read the Daily Mail every day: but sometimes, out of the corner of my eye, I worry that it might infect me. We are all biased by the information we expose ourselves to, through our friends, our reading, and our choices in life.

I think science coverage is pretty poor, and a lot of it is plainly wrong.

Gary Schwitzer used to be a journalist, but now he has turned to quantitative analyses of journalism, and this month he published an analysis of 500 health articles from mainstream media in the US. The results were dismal.

Only 35% of stories were rated satisfactory for whether the journalist had "discussed the study methodology and the quality of the evidence": because in the media, as you will have noticed, science is about absolute truth statements from arbitrary authority figures in white coats, rather than clear descriptions of studies and the reasons why people draw conclusions from them.

Only 28% adequately covered benefits, and only 33% adequately covered harms. Articles routinely failed to give any useful quantitative information in absolute terms, preferring unhelpful eye-catchers like "50% higher" instead.

Was this new? No. The same thing has been shown in Canada and Australia, and in the US almost a decade ago. Does it matter? Yes. Regardless of what they say in surveys about trusting doctors and priests, and despising hacks, in reality, people listen to journalists. This is not idle speculation.

A 2005 study in the Medical Journal of Australia looked at the impact of Kylie Minogue's breasts on mammogram bookings. They rose by 40% during the two-week publicity peak, and six weeks later they were still up by a third. The increase among previously unscreened women in the 40-69 year age group was 101%. These surges were unprecedented.

Am I cherry picking? A systematic review from the Cochrane Collaboration found five studies looking at the use of specific health interventions before and after media coverage of specific stories, and each found that favourable publicity was associated with greater use, and unfavourable with lower.

And it's not just the public: medical practice is influenced by the media too. Coverage of a flesh-eating bacteria outbreak led to a massive increase in group A streptococcus screening in one accident and emergency department (from 55 to 103 per 1,000 visits).

But even academics are influenced by media coverage: a seminal paper from the New England Journal of Medicine in 1991 said that if a study was covered by The New York Times it was significantly more likely to be cited by other academic papers. But for three months large parts of the NYT went on strike. The journalists wrote stories about academic research which never saw the light of day. The research saw no increase in citations. People read newspapers.

Despite everything we think we know, their contents seep in, we believe them to be true, and we act upon them.

· Please send your bad science to bad.science@guardian.co.uk