Summer is here and my favourite scare mongers are at it again. They are putting out dire warnings of the risks of using sunscreens if you don’t first check with them and then buy the ones they recommend. I am sure readers of Colin’s Beauty Pages are savvy enough to see through anything so transparently self serving.
One argument I have seen put forward online against these scare tactics is to say that far from causing skin cancer sunscreens do in fact protect against skin cancer. It sounds plausible, but is there any evidence?
In the area of health, a lot of things that get trotted out as facts turn out to be short of back up when you look into it. They may be true – but there is no actual proof. I have totally failed to find any evidence that the risk of diabetes is increased by being overweight for example. There probably is a link. People who work in the area believe it is true and the chances are they are right. Gut feelings often are. I am happy to follow an intelligent experienced expert’s gut feeling. But I am happier still if there is real evidence behind it.
The idea that sunscreens protect against cancer is not totally unjustified. There is some work that bears it out, but it isn’t particularly well known. I have a feeling I wouldn’t know about this study if I hadn’t been at a Dermatology conference in New Orleans in 2002 where one of the authors gave a talk on it. It wasn’t published at that stage. She started the talk with a review of the evidence which had been gathered up to that point. It was patchy, but suggestive that there was an anti-skin cancer benefit from using sunscreens. It was all a bit scant – suggestive but hardly conclusive.
So dermatologists in Australia, where skin cancer is a huge problem, did a serious prolonged study of the incidence of two kinds of cancer: squamous and basal cell carcinomas. Two groups were studied – one group with and one without daily use of sunscreen. Over the 4.5 years of the study, the group on the sunscreens experienced significantly lower levels of the squamous cell form. There was no difference in the basal cell carcinoma incidence. The followed up 8 years after the completion of the study and found that the effect was a long term one. Quite an impressive one for the squamous cell carcinoma with the sunscreen treated group showing 40% lower incidence level.
But the basal cell carcinomas were the same in each group. This is both the more common and the harder to treat of the two cancers studied, so it is disappointing that no benefit was found.
So for what it is worth, I think sunscreens probably do protect to some extent against cancer but it is far from a well established fact. It doesn’t look at all likely that sunscreens themselves are actually carcinogenic based on this data, so that is good. The critics of sunscreens don’t bother too much with evidence so they are unlikely to let this study change their tune. But it has to be said that it doesn’t look like sunscreens are the ideal solution to the problem. I’d take a 40% reduced risk of the second most common form of skin cancer as well worth having, but it falls short of what I’d describe as ‘protection’. Especially when it does so little against the more common form. The search needs to be on for something a lot better.
As to people who confidently assert that you need to have at least SPF15 and preferably SPF30, well they may well be right but lets be clear that they are offering an opinion not a fact.
And as it often turns out, on investigation it turns out that a lot of what is said about an important subject is based on surprisingly thin foundations.
Don’t get me started on global warming…..
This is the paper reporting the very good Australian study I discuss above.
Thanks to gazzaPax on Flickr for the rather natty image.