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Implications for practice and research
To date, ultraviolet (UV) exposure is the only environmental factor associated with an increased risk of melanoma.
There is therefore a need to ensure that the risks associated with artificial UV exposure are quantified.
There has been some controversy regarding the association between melanoma and sunbed exposure as some studies have shown positive associations while others have not.
Melanoma has long been linked to UV exposure and this has been established via case-control studies and cohort studies including migration studies from Australia and Europe as well as laboratory studies on animal models. Most case-control studies have shown that exposure to natural sunlight is associated with an increased risk of melanoma, especially for exposure before the age of 35 years and overall relative risk of 1.75.1 Artificial UV exposure has also been of interest over the last 30 years with many case control studies and cohort studies.
This meta-analysis was an update from a meta-analysis published by a working group from IARC involving the same authors and published in 2007 with eight additional studies identified since then.1 After selecting those studies which fulfilled the criteria, this review included 28 studies on sunbed use and melanoma between 1981 and 2012. Eighteen studies were based in Europe and the rest in the USA, Canada and Australia. The review included 11 428 cases of melanoma. The summary relative risks were calculated using a random effect model. The authors were also able to examine dose responses whenever these data were available. They also estimated the relative number of deaths in Europe from melanoma attributable to sunbed exposure.
This meta-analysis reported increased, albeit small, relative risks for melanoma in association with sunbed exposure but in some instances the CIs included 1 or were very close to 1. There was stronger evidence of a risk, as previously reported, for sunbed exposure below the age of 35 years. This meta-analysis also found a dose response with increasing risk of melanoma associated with increasing sunbed exposure, but this did not reach statistical significance unless the exposure was very high. Latitude did not affect the association. The authors also estimated that 3438 new cases of melanoma and 794 deaths in Western European countries were attributable to sunbed exposure. The risk of squamous cell carcinoma in association with sunbed use was significant and slightly higher than for melanoma but these results were based on a limited number of studies. The risk associated with basal cell carcinoma was lower and barely reached statistical significance.
This review reports an increased risk of melanoma with sunbed use. However, it is important to note that even with a large number of melanoma cases and controls, some of the results failed to reach statistical significance. Exposure before the age of 35 years of age appears to be more detrimental with significant relative risks. Higher risks were reported with increasing use of sunbeds, but only if exposure was very high. The authors comment that the melanoma epidemic in Iceland in 1999 may be attributed to sunbeds, and the subsequent decrease in incidence in 2000 explained by public health campaigns. However, this would not fit with the long lag time between exposure and disease which is unlikely to be only 1 year for melanoma. The number of deaths from melanoma in Europe caused by exposure to sunbeds is very difficult to estimate. Melanoma, like all cancers, is a multifactorial disease with complex interactions between genetic factors and the environment so it is very difficult to estimate with accuracy the true impact sunbeds have had on mortality in Europe, especially as sun, sunbed exposure and skin type are not easy to dissociate. However, it may, as suggested by the authors, be difficult to estimate the eventual impact of current exposure to sunbeds, which has increased dramatically over the last 20 years. Individuals at high risk of melanoma—those with large number of moles, very fair skin or an inability to tan as well as those below the age of 18 should be advised not to use sunbeds (not all European countries have regulations regarding use in children as in the UK). What is more important is public education and education of staff in tanning salons so that individuals at high risk of skin cancer may be identified and advised not to use them. The gradient of sunbed use from northern to southern Europe with higher use in the north cannot be ignored; and there are reasons other than tanning which explain why sunbeds are so popular in northern Europe such as mood enhancing during long winters.2 However, it is easy to generate enough vitamin D synthesis with short and safe exposure to natural sunlight and supplementation if necessary, so the need to use sunbeds for that purpose should not be recommended.3
Competing interests None.
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