Michael JensenDo moisturisers really help cause skin cancer?
August 15th 2008 09:45
Sunbaking is never a good idea but can moisturisers really contribute to skin cancer? (pic: theage.com.au)
The reason the scientists chose to look at moisturisers was that they contain sodium lauryl sulphate or mineral oil and these are known irritants. It would appear their hypothesis was that irritating the skin somehow increases the skin's susceptibility to UV radiation, and thus increases the risk of developing skin cancer.
Professor Allan Conney, said his findings "could help explain the incidence of some types of skin cancer in patients," especially those who have had lots of sun exposure."
Holy crap! I hear you say. Well, yes, that was my first reaction too. That's terrifying and to anyone who isn't listening, or willing to go past the first paragraph of the story it most certainly will remain so.
But if you go on, you'll read you'll read that dermatologists and scientists are saying the study is "highly artificial" and "premature, unhelpful and even irresponsible".
Why? The researchers used hairless mice and have not investigated any of this in humans. They used a cream that didn't contain the irritants and compared it to creams that did, showing that the irritant-laden creams significantly (ie statistically) increased tumour rates.
In perhaps the biggest understatement of 2008, Prof Conney acknowledges the significance in humans is still "unknown" and more studies are needed.
Now, I've only been able to get to the abstract, and I may be reading it incorrectly, but it appears they irradiated the mice for three weeks before adding the creams - and that these treated mice developed more tumours that grew more rapidly than the ones who didn't get the cream.
I cannot see the data so cannot comment further but I wonder if they took into account the way humans and mice differ (yes, we are similar in many respects but we're importantly we're quite different in others) or whether the irritants act on the skin's ability to mop up the cells damaged by UV radiation... I feel a rant coming on so will stop.
You cannot control everything in any experiment - you do your best to account for the variables and I'm sure these people are well-intentioned - but to make a sensational and alarmist claim such as this you would want to be damn certain of your results.
A study such as this does have a place in a dermatological journal and in time it may prove to be valid but the irresponsibility comes in talking to the media about it at this early stage. Cancer is no trifling matter and I cannot think of a single good reason why scaring people like this without conclusive evidence in humans can be justified.
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