Sunbeds cause skin cancer – the evidence is clear

• Updated below

We’ve known that using sunbeds can cause skin cancer for several years.

And this week this message became louder and clearer than ever before with the publication of the strongest evidence yet of the link between the tanning devices and skin cancer.

In this post we’ll look at some of what we already knew about sunbeds and skin cancer, what this new study adds, and what we should be doing about it.

What we already knew

Sunbeds were first classified by the International Agency for Research in Cancer (IARC) as ‘Group 1 carcinogens’ in 2009 – we blogged about this at the time. This classification – which means that there’s clear evidence of a link – followed the publication of a thorough review of the available evidence. It showed that people who start using sunbeds before the age of 35 have a 75 per cent increased risk of malignant melanoma, the most serious form of skin cancer.

What’s in the new study?

This new research, published in the BMJ, updates this previous study by including eight more studies, bringing the total number analysed to 27.

The new results showed that people who had ever used a sunbed were 20 per cent more likely to subsequently develop melanoma, compared to people who had never used one. And when the researchers controlled for other factors that influence melanoma risk like sun exposure and sun sensitivity the increase in risk became larger –  29 per cent (we’ll talk more about these ‘relative’ risks later).

Although the previous study also found an increased risk for such ‘ever users’ (this group includes all ages who have used a sunbed), it wasn’t statistically significant, meaning the researchers couldn’t be sure if the result was due to chance. This new analysis included more sunbed users than the previous study, and confirms that it’s not just younger sunbed users who are at an increased risk of melanoma.

But the study did reiterate that young people are particularly at risk when they use sunbeds. People who started using sunbeds before the age of 35 were 87 per cent more likely to develop melanoma (an update on the previous estimate of 75 per cent) compared to people who have never used a sunbed.

So this new study constitutes conclusive evidence that people who’ve ever used a sunbed have a higher risk of melanoma, and and that there’s even higher estimate for the risk for people who start using sunbeds before age 35.

The authors also looked to see if the risk of developing melanoma increases with increasing number of sunbed sessions. Their data suggested that each extra sunbed session a person has every year increased their melanoma risk by 1.8 per cent. But this result wasn’t statistically significant, so we will have to await further studies before we can be sure of this figure.

How many cases of melanoma do sunbeds cause?

The numbers we’ve given above are so-called ‘relative’ risks – they compare the rates of cancer between two different groups (in this case, sunbed users versus non-users) and work out the percentage difference. But what about the absolute numbers? How many people are affected?

The authors estimate that sunbeds are responsible for 3,438 (5.4 per cent) out of 63,942 malignant melanoma cases in the 18 European countries studied. For the UK, they estimate that sunbeds cause about 440 malignant melanomas each year – more than one a day – and just under one hundred deaths. They base this estimate on 2008 statistics, which show there were around 11,600 new cases of malignant melanoma and around 2,000 malignant melanoma deaths in the UK.

According to the latest data, there were 12,800 new cases of malignant melanoma and around 2,200 deaths from malignant melanoma in the UK in 2010.

It’s important to emphasise that the authors calculations are just estimates, and that there are several reasons why we need to be careful when using them, including one intriguing hypothesis that sunbed-induced melanomas are slightly different to those caused by the sun, and may have a different mortality rate.

Compared to the overall number of cases, the 440-odd cases caused by sunbeds each year might seem comparatively small. (UV exposure from the sun is the cause of most melanomas). But these cases caused by sunbeds are entirely preventable.

Other types of skin cancer

Importantly, the study also found that using sunbeds increases the risk of two other types of generally less serious but far more common types of skin cancer too.

The risk of basal cell carcinoma increased by nine per cent compared to people who’d never used a sunbed, and the study also confirmed that risk of squamous cell carcinoma more than doubled.

So what’s the take home message?

It’s now clearer than ever that sunbeds are not a safe alternative to tanning from the sun. There’s now strong evidence that people who have ever used a sunbed have an increased risk of melanoma – the most serious form of skin cancer – and this risk is even higher in people who start using sunbeds before the age of 35.

To re-iterate what we said above, the increased risk of skin cancer from sunbeds may be relatively small, but it is completely avoidable. Cancer Research UK will be using the findings of this and other studies to continue and strengthen our work to protect children and young people from sunbeds, and to warn adults of the dangers.

Whether you’ve used sunbeds before or not, it’s a good idea to keep an eye out for unusual changes to  your skin, particularly any changes in the size, shape or colour of a mole, freckle or normal patch of skin. It probably won’t be cancer, but we know that cancer is usually easier to treat when it’s diagnosed at an early stage.

Claire

UPDATED – 23rd Jan 2013

The authors of the study discussed in this post have issued a correction for one of the figures in their research paper. Due to a corrupted data file the authors wrongly reported that people who start using sunbeds before the age of 35 have an 87% increased risk of malignant melanoma. This figure has now been amended to 59%.

All the other figures in the paper remain unchanged. This doesn’t alter the evidence that, irrespective of age, people who have ever used a sunbed have a higher risk of melanoma and other types of skin cancer than those who have never used one. And this revised figure still shows that using a sunbed before the age of 35 raises skin cancer risk more still.

Further information

• NHS Choices have a nice summary of the main findings of the research
• SunSmart – Skin Cancer Information and Sun Protection Advice 

Reference

• Boniol, M., Autier, P., Boyle, P. & Gandini, S. (2012). Cutaneous melanoma attributable to sunbed use: systematic review and meta-analysis, BMJ, 345 (jul24 2) e4757. DOI: 10.1136/bmj.e4757