Friday, November 02, 2007

Here we go again

Another "expert panel", would you believe -- with TOTALLY predictable conclusions. The medical establishment has reasserted its current beliefs. A pity they regularly retreat from previous "wisdom", though. One has to laugh about the report being based on the "best 7,000" studies. Studies with pesky conclusions were no doubt excluded from being "best". The repeated finding that it is people of middling weight who live longest was obviously not "best", for instance

Being even slightly overweight can increase the risk of a range of common cancers including breast, bowel and pancreatic cancer, a landmark study has found. The largest review of links between diet and cancer, incorporating more than 7,000 studies, concludes that there is convincing evidence that excess body fat can cause at least six different types of the disease. The researchers give warning that everyone should be at the lower end of the healthy weight range.

Their recommendations include avoiding processed meats such as ham, bacon, salami or any other meat preserved by smoking, curing or salting; only consuming small amounts of red meat; moderate consumption of alcohol; and avoiding junk food and sweet drinks.

Professor Sir Michael Marmot, who chaired the expert panel assembled by the World Cancer Research Fund (WCRF) to review evidence on the dietary causes of cancer, said he had been shocked to find that weight was so important. A report by the fund published ten years ago linked only one cancer to being overweight. Professor Marmot said the evidence now showed that at least six - cancers of the oesophagus, pancreas, bowel, breast postmenopause, kidney and endometrium (womb lining) - were linked and that the risks were increased by even quite modest weight gains. The finding is particularly alarming, given the expanding girth of the British population. An official report last month gave warning that by 2050, 60 per cent of men, 50 per cent of women and a quarter of all children could be clinically obese. A healthy weight is defined as having a body mass index (BMI) below 25; BMI is calculated by dividing an individual's body weight in kilograms by the square of the height in metres.

Picture of a Marmot above. Is that you, Sir Michael?

Sir Michael said: "A BMI of 25 is fine, but it would be a bit finer if it was lower. The healthiest thing is to be as low as possible within the normal range." The report suggests moderation in the consumption of red meat, suggesting a limit of 500g (18oz) per person per week. A total avoidance of processed meats is recommended because of convincing evidence that eating meat increases the risk of colon cancer.

The WCRF report emphasises the benefits of exercise, for its direct effects on some cancers, and because it helps to prevent becoming overweight or obese. It made ten recommendations which do not, save in one case, conflict with advice given for the avoidance of other common causes of death, such as heart disease. The exception is alcohol, which Professor Marmot said had been shown to cut the risk of heart disease. For cancer prevention the optimum level is zero, but for heart disease it is two units a day for men and one for women, he said. The panel agreed that the levels set for minimum heart risk should be accepted.

The report is based on an analysis of cancer studies from around the world dating back to the 1960s. The initial trawl produced half a million studies, which was pared down to the best 7,000. The results were analysed by nine teams and then presented to a panel of twenty-one leading scientists for their recommendations. They looked at cancers at 17 different sites in the body and at a wide range of factors, mostly dietary, that can affect risk of developing the disease.

Professor Marmot said: "We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood. This might sound difficult but this is what the science is telling us more clearly than ever. The fact is that putting on weight can increase your cancer risk, even if you are within the healthy range."

Dairy foods, cheese, butter, coffee and fish get a clean bill of health. But sugary drinks - including fruit juices - can increase weight and are therefore not recommended. Nor are fast foods because they are energy-dense and lead to excess weight or obesity, which in turn increase cancer risks.

Professor Martin Wiseman, the project director, said: "This report's recommendations represent the most definitive advice on preventing cancer that has ever been available anywhere in the world."

Breast-feeding has a double benefit, the report says, protecting mothers against breast cancer and their babies against obesity. Mothers were advised to breastfeed exclusively for six months and to continue with complementary breastfeeding after that.

Dietary supplements for cancer prevention were not recommended, since there was evidence that at high doses they could have adverse effects. But selenium, in the diet or as a supplement, did appear to have benefits against lung, colon and prostate cancer.

Professor Mike Richards, the Government's clinical director of cancer, said: "The WCRF report is the most authoritative and exhaustive review done thus far on the prevention of cancer through food, nutrition and physical activity. For those of us wanting to lower our risk of developing cancer, it provides practical lifestyle recommendations."

Karol Sikora, Professor of Cancer Medicine at Imperial College School of Medicine, said: "The educational message for the public should be that there are healthy diets and unhealthy diets, but we should keep everything in perspective and not suggest rigid avoidance. Alcohol, red meat and bacon in moderation will do us no harm, and to suggest it will is wrong."

Chris Lamb, consumer marketing manager at the British Pig Executive, said that people should continue to eat bacon "in a responsible way as part of a balanced diet". Cancer was a "complicated subject" and could not be prevented simply by reducing intake of meat. "Two thirds of all cancers are not caused by diet. Just by addressing the meat issues, you are not necessarily going to prevent cancer," he said. Mr Lamb said that the average consumption of red meats was less than 500 grams per week in any case, so many people did not need to change their eating habits at all. He added that there were concerns amongst farmers that sales of processed meats could fall as a result of the report. "That is obviously a potential at the end of the day, but we're hoping that consumers will think about being responsible in overall terms.


Prostate cancer in Britain and the USA

Paul Krugman has attacked Rudy Giuliani for a dishonest ad on health care--or perhaps an ignorant one, as the case may be. This is a test for the media, as well as a scandal in its own right, Paul says. Will those feckless reporters and editors at The New York Times call Giuliani to account for this? Probably not, seems to be Paul's opinion:
OK, Rudy Giuliani has just released an ad claiming that the survival rate from prostate cancer is much higher in America than in Britain, thus proving the failure of socialized medicine.

The problem is that his claim is just plain false. In fact, mortality rates from prostate cancer are almost the same in America and Britain.

So, will this get as much attention as, say, the Edwards haircut or the Hillary laugh? Will it get any coverage at all? Bear in mind that health care is the central domestic issue of this election — and Rudy has just showed that he doesn’t know a thing about it.

Giuliani's claims in the ad are indeed misleading. First, prostate cancer is a very bad example. Worse, in my view, is the implication that his Democratic opponents are proposing "socialised medicine" remotely similar to  Britain's NHS. That can only be a deliberate deception.

To say that prostate cancer survival rates are much higher in the US than in England is not "just plain false", however. It is just plain true. Five-year survival rates are higher in both America and England than Giuliani said. In the United States they stand at close to 100 per cent. In England they are 25 points lower. Figures for prostate cancer are notoriously misleading, though, because early detection (at which the US excels) delivers little improvement in mortality.

Chiefly because of better diagnosis, America records a far higher incidence of prostate cancer--and nearly all of those early-detected cases survive five years. Men with prostate cancer, which develops slowly, often die of something else. If you are a man with prostate cancer, it may not matter very much whether your cancer is diagnosed early, or whether you live in Britain or America.

But does Paul therefore think that cancer survival rates, correctly measured, are similar for all cancers, including those for which early detection is important? If so, he is mistaken. See this report, entitled "Cancer Survival Rates Improving Across Europe, But Still Lagging Behind United States" (and remember that England's rates, not broken out, are among the worst in Europe).

Taking recent figures, female five-year cancer survival rates are 62.9 per cent on average in the US and 52.7 per cent in England. To compare America's privately insured with England's NHS patients, you'd need to bump up that American survival rate a bit (the uninsured most likely have lower survival rates--otherwise why worry about universal coverage) and bump down the English one (because some Brits have private insurance, and so buy better care).

Nationally, American cancer survival rates are significantly better. Certainly not by the 40-point margin Giuliani implied, but still. And the politically salient question is this: If you have cancer, would you rather be an American with insurance or an Englishman without? The answer is obvious.


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