Risk of common skin cancer increased by as much as 90 percent, study finds

Research that was presented at the World Congress on Cancers of the Skin in Edinburgh, Scotland, shows that sunbeds significantly increase the risk of a potentially serious skin cancer that is twice as common as melanoma.

Warnings about sunbeds often focus on melanoma, the least common type of skin cancer, which is linked to sunburn. Some sunbed operators therefore claim that as long as skin does not burn, there is no cancer risk.

However this latest warning, from researchers at University of Dundee in Scotland and Leiden University Medical Centre in the Netherlands, relates to squamous cell carcinoma (SCC), the second most common type of skin cancer. SCC is caused by longer-term, cumulative exposure to UV, such as through repeated tanning, rather than isolated incidents of burning. SCC accounts for about 20 per cent of all skin cancers, while melanoma accounts for just one per cent.

In January 2013, the same researchers from Dundee published a study which measured ultraviolet (UV) radiation levels emitted by 402 sunbeds across England*. This showed that nine out of ten sunbeds emitted UV levels that exceed European safety limits.

In this latest study, the team used these data on the UV intensity levels, factored in the average length of sunbed sessions, and the number of sessions each year, as well as a person’s cumulative UV exposure from the sun, and then applied an equation that links UV exposure and SCC incidence, to predict risk to people who use sunbeds.

The researchers found that by 55 years of age, people who used a sunbed were 90 per cent (1.9-fold) more likely to develop SCC than those who did not. Sunbed use was defined as having a 12 minute session about every eight days (or a six minute session every four days), over a 15 year period from age 20 to 35 years, using a sunbed with a median UV dose**. For high dose sunbeds the risk is increased by 180 per cent. Even the sunbeds giving the lowest UV dose found in the 2013 study were linked to a 40 per cent increased risk of developing SCC.  

This is the first study to estimate the risk of SCC according to the type of sunbed (high, medium and low output), session time, and number of sessions per year, and consider those in relation to day-to-day exposure and holiday exposure.

Professor Harry Moseley of the University of Dundee, one of the study’s authors said: “There is considerable variation in the output of artificial tanning units which people should be aware of. The results of our study indicate that the additional UV dose from sunbed use compared to normal day-to-day sun exposure potentially adds a significantly increased risk for development of SCC.”

Nina Goad of the British Association of Dermatologists said: “While other types of skin cancer, such as melanoma, are linked to sunburn, SCC is caused by more chronic, long-term, cumulative sun exposure. One defence of the sunbed industry is that sunbeds do not increase your risk of skin cancer if you do not burn, however this study weakens this argument. It is something that people should be warned about, so they are fully informed of the risks when making choices about sunbed use.”

There are two main types of skin cancer: melanoma and non-melanoma skin cancer. SCC is a non-melanoma skin cancer, and the second most common type of skin cancer in the UK. While it results in fewer deaths than melanoma (approximately 500 SCC deaths per year in the UK compared to 2,200 deaths from melanoma), it has metastatic potential (it can spread to other parts of the body) and can have a significant impact on the patient, including extensive scarring following surgical removal.

The most common cause is too much exposure to ultraviolet (UV) light from the sun or from sunbeds. This causes certain cells (keratinocytes) in the outer layer of the skin (the epidermis) to grow out of control into a tumour. SCC can be cured if detected early, however if an SCC is left untreated for too long it may spread to other parts of the body, which can prove fatal. About 23,600 new cases of SCC are diagnosed in the UK each year. However, as not all cases are registered, the actual figure is believed to be far higher.

-Ends-

Notes to editors:

*http://www.bad.org.uk/media/news?SiteSectionId=154&page=3&from=01/01/2013%2000:00:00&to=01/01/2014%2000:00:00&range=2013    

** A Standard Erythemal Dose (SED) is a standard measure of UV dose. The median total sunbed irradiance was calculated to be 0.54 Wm-2 which is equivalent to 3.9 SED for a 12 minute sunbed session. High dose is defined as 302 SED and low dose as 82 SED.

For more information please contact: Matt Gass, Communications Officer, on 020 7391 6084 or at matthew.gass@bad.org.uk

If using this study, please ensure you mention that the study was released at the World Congress on Cancers of the Skin. 

The conference will be held in Edinburgh from September 3rd to 6th 2014, and is attended by approximately 1,000 UK and worldwide health professionals.

The World Congress on Cancers of the Skin 2014 was founded by The Skin Cancer Foundation, the international organization devoted solely to education, prevention, early detection, and prompt treatment of the world’s most common cancer. It is organised by the British Association of Dermatologists.

Study details:

156, Predicted increased risk of squamous cell carcinoma induction associated with sunbed use, Patrick Tierney1, Sally Ibbotson1, Frank de Gruijl2, Harry Moseley1, 1Photobiology Unit, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK, 2Dept. of Dermatology, Leiden University Medical Center, Leiden, The Netherlands

Solar Ultraviolet (UV) radiation is acknowledged as the principle cause of skin cancer. Furthermore, sunbeds have been classified as carcinogenic by International Agency for Research on Cancer.  Therefore an increased risk of developing non-melanoma skin cancer (NMSC) is expected when one is exposed to both sources of UV radiation. The additional risk factor was determined from a squamous cell carcinoma (SCC) tumour induction model based on albino mice1. The risk model for SCC induction was adapted to include the use of sunbeds2 along with lifetime cumulative dose from day-to-day and holiday exposure.  The latter two were established as the “baseline” exposure. Age and environmental UVR exposure are the two most important factors in determining the relative risk. Application of meta-analysis with biological amplification factor 2.3 and age dependent factor 3.8 from epidemiological studies is used to estimate risk of SCC associated with the extra dose accumulated with sunbeds. The relative risk was defined as the risk of SCC induction from (sunbed + baseline) / baseline. We additionally investigated the various body-sites, from those normally exposed such as face and arms to more usually unexposed sites. With these scenarios the relative risk of SCC induction from median sunbed exposure output in addition to median baseline sun exposure level was 1.9 at age 55 years. This is the first time that a risk model for skin carcinomas has been developed that includes real sunbed exposure data. It shows that the additional risk associated with sunbed use may be significant, particularly when high output, fast tan sunbeds are used.

1De Gruijl FR, Van der Leun JC. Development of skin tumors in hairless mice after discontinuation of ultraviolet irradiation. Cancer Research 1991; 51: 979-84.
2 Tierney P, Ferguson J, Ibbotson S et al. Nine out of 10 sunbeds in England emit ultraviolet radiation levels that exceed current safety limits. British Journal of Dermatology 2013; 168: 602-8. 

About the BAD 

The British Association of Dermatologists (BAD) is the central association of practising UK dermatologists. Our aim is to continually improve the treatment and understanding of skin disease. The BAD provides free patient information on skin diseases and runs a number of high profile campaigns, including Sun Awareness, which runs from May to September annually and includes national Sun Awareness Week in May. Website: www.bad.org.uk/sunawareness

Published on September 2, 2014