LETTERS
Burger — the facts
Sir: I'm shedding crocodile tears at Stephen Glover's scathing criticism (Media studies, 24 August) of my front-page story in the , previous week's Observer. He even doubts whether the scientists at the University of Iowa have really found that hamburgers pose a significant risk in the development of non-Hodgkin's lymphoma. 'Have they?' he asked. 'It would be jolly interesting to hear those scientists speak for themselves.'
The research team leader was Dr James Cerhan MD, PhD, and, yes, he did speak for himself. He and his colleagues pub- lished their research — it was the lead paper — in the Journal of the American Medical Association, one of the world's most respected medical journals, and one that has its papers reviewed by other scien- tists before publication.
This process of peer review is designed to weed out glitchy papers and it generally works rather well. Dr Cerhan's team stud- ied 35,000 Iowa women for seven years and the research is continuing. Non-Hodgkin's lymphoma is, after skin cancer, the West- ern world's fastest-increasing" cancer, and many people want to know why.
Statistical analysis of Dr Cerhan's research showed that the P-value of the association between burgers and cancer was 0.05. In lay terms, this means that there was only a 5 per cent chance of his findings being caused by chance. In medical research a P-value of 0.05 or less is the gold standard of significance. It is unlikely that JAMA, as it is known to its readers, would have published this research without proper analysis.
Dr Cerhan is a leading epidemiologist, and he told me, when we discussed his research, that the greatest single risk factor for NHL, as it is called in the medical trade, is having a previous blood transfusion. This is one of the reasons why doctors are no longer sanguine about giving blood. The second greatest risk factor is, as we've just mentioned, burger-eating.
If Dr Cerhan's paper had been pub- lished in the British Medical Journal it would have made immediate front-page headlines here. This is because UK medi- cal correspondents get an advance copy of the Journal. The doctors would have read about it, because they get the BMJ free with their BMA subscription.
Caroline Richmond
21 Stratford Grove, London SW15
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