Friday, 30 March 2012

Health Scare Story Du Jour

From the BBC:

Obesity is fuelling a major increase in the number of cases of kidney cancers diagnosed in Britain, experts say.

Cancer Research UK has published figures showing there were just over 9,000 cases in 2009, compared with just under 2,300 in 1975. Obesity increases kidney cancer risk by about 70%, compared with smoking which increases it by about 50%.

Cancer Research UK says too few people understand the cancer risk of being overweight. Kidney cancer is now the eighth most common cancer.


As per usual, it's made up figures time. The chances are there were plenty of kidney cancer deaths in 1975, they just weren't diagnosed or recorded as such. If there are 9,000 'cases' out of over sixty million people, of whom at least fifteen million have been aribtrarily classified as 'obese', that isn't terribly many. And what's a 'case'? A 'death' I understand, but how many of those 'cases' are treated successfully? An increase in the risk of 70% is meaningless unless you know the absolute risk to start off with, either way, only about a third of those 9,000 'cases' are down to obesity*. Smoking looks relatively safe, and if it is indeed true that smoking helps weight loss (supresses appetite), then an obese person can reduce his kidney cancer risk by having a cigarette when he feels hungry. And 'eighth most common cancer', what? What relevance does that have to anything? At a guess, that's only a couple of per cent of all cancer 'cases'. CRUK is a fakecharity. And so on.

* 45 million x normalised risk 1 = 45 million
15 million x heightened risk 1.7 = 25.5 million
25.5 + 45 = 70.5
25.5 ÷ 70.5 = 36%, a bit more than a third.

4 comments:

Anonymous said...

And what's a 'case'?

Someone who is found to have kidney cancer.

A 'death' I understand, but how many of those 'cases' are treated successfully?

The article didn't claim that being overweight increases your chance of DYING from kidney cancer.

if it is indeed true that smoking helps weight loss (supresses appetite), then an obese person can reduce his kidney cancer risk by having a cigarette when he feels hungry.

But will increase the general risk of cancer from smoking.

But yeah, 9000 diagnoses is not that high. I wouldn't base a decision to smoke or gorge on food on the chance of getting this cancer. It would also be accurate to conclude that having kidney cancer increases your risk of being overweight.

Anonymous said...

1. There were less people in the UK in 1975.
2. What is the age spread of these cases? Is this mainly a disease of old age? If it is, then as we are living longer, more people will get it (as is the case with pretty much all cancers).

I am calling this one yet another fake call for more of our tax money.

Mark Wadsworth said...

J, fair enough.

Mr C, point 1 is not so relevant, population only up by a fifth or so, but your point 2 is brilliant, I hadn't thought of that.

Anonymous said...

Thank you Mark.

This is a point that should always be borne in mind when these people come out with their press releases. That and the risks, both absolute and relative. As you point out above, absolute risk was, and remains tiny. Relative risk (RR)for obesity 1.7 (70% increase) is just bollocks and meaningless. Anything below RR 2 (100% increase) can be happily filed in the round file under your desk and ignored. That includes pretty much any study on second hand smoke, and any health story in the Daily Mail.

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