Do moisturisers cause skin cancer?

A study by Canadian researchers has produced some interesting and unexpected results.  They had set out to test an idea that caffeine might help in the control of skin cancer.  I am not sure where they got this idea from but the way they proposed to go about trying it out was quite logical.  They exposed some hairless mice to UV radiation.  This is a sure way to induce skin cancer.  They were then going to run a group with the caffeine applied in a cream and a group with  the cream on its own.  But they were very diligent even by scientific standards and before they started they tried out the cream base on its own.

To their surprise, they found that the cream itself increased the speed at which the cancer developed.  They tried three other brands of cream and got the same result.

These results surprised me as well.  What didn’t surprise me was the response from the manufacturers of one of the creams who almost instantly weighed in criticising the research and trying to rubbish it.  This is probably a complete waste of time.  When you suggest a link between a product and cancer not many people are going to be swayed by minor methodological issues.  Reading the paper it seems to have been a solid bit of work.   Science progresses by exactly work like this.  When you get an observation that contradicts what you believe to be true then it is time to look at your ideas.

The skin has some pretty effective protective mechanisms.  These are biochemical processes that work better in well moisturised skin.  So I would have expected that a moisturiser would be beneficial.  Have I completely misunderstood the situation?  Well maybe.  But having thought it over I think I can explain the results without resort to a major rethink.  The mice were irradiated and had contracted the cancer before the cream was applied – so there is no reason to believe that the cream itself caused the cancer.  Increasing the flow of blood and nutrients to the skin should improve the health of the skin.  I think that the cancer cells are simply being provided with a better environment in which to grow.

My conclusion – I don’t think that there is yet any reason to think that moisturisers actually make skin cancer worse.  In this experiment the cancer was caused by the UV, not the moisturiser.  In the case of these particular hairless mice, the moisturiser speeded the development of the cancer.  Moisturisers increase the water level in skin and this speeds up whatever biochemical processes are going on there.  For the mice, this means that the cancer had a better environment to grow.  On healthy human skin it is more likely to be beneficial.

I am going to carry on moisturising until there is clearer data that moisturisers are harmful.  On balance, I still think that they are beneficial.

Reference

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2630214/?tool=pubmed

3 thoughts on “Do moisturisers cause skin cancer?

  1. Perry

    Interesting study and explanation. The other thing I would add is that one study (wonder if this has been repeated) is never enough to completely change a paradigm. It is just another bit of data to be piled on the mounds of data collected before it. For scientific conclusions we need to compare the weight of the data, not just a single study. Are there any studies that further support this conclusion? I haven’t seen any.

    While reading I did think of a study that could be run to answer more questions. First, there should have been a control of non-UV-exposed mice who also got skin lotion. Second, to test your moisture theory, an application of petrolatum could have been used. Then an application of some other moisturizing material could be tested to see if both of them had the same effect.

    Interesting stuff. I wonder what has been done since.

  2. Perry

    I just looked at the abstract and saw that they tested a Custom Blend lotion that didn’t have the effect.

    However, the Custom Blend didn’t contain any petrolatum or mineral oil so I can see that your explanation still makes sense. The Custom Blend lotion just didn’t do a good job of moisturizing.

  3. Colin

    Good points Perry. I would really like to see your experiment done.

    No follow up has been done on this that I am aware of. There isn’t any obvious reason it has started getting publicity again recently, other than there are lots of people looking desperately for evidence that there is something wrong with cosmetics and not finding very much. So this one gets churned out again.

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