Sunbeds and Melanoma Risk: Many Open Questions, Not Yet Time to Close the Debate

BACKGROUND

Intensive scientific debate is ongoing about whether moderate solarium use increases melanoma risk. The authors of some recent publications demand the debate be closed and propose "actions against solarium use for skin cancer prevention" because new studies have convincingly demonstrated causality. This minireview aims to investigate whether those demands are sufficiently supported by present scientific knowledge and comply with the principles of evidence-based medicine.

MATERIALS AND METHODS

We performed a systematic literature search (through June 2019; PubMed, ISI Web of Science) to identify publications investigating how solarium use affects melanoma risk.

RESULTS

We found no studies that demonstrate a causal relationship between moderate solarium use and melanoma risk. Results of cohort and case-control studies published to date, including recent investigations, do not prove causality, and randomized controlled trials providing unequivocal proof are still lacking. Moreover, the overall quality of observational studies is low as a result of severe limitations (including unobserved or unrecorded confounding), possibly leading to bias. We also disagree with recent claims that Hill's criteria for the epidemiological evidence of a causal relationship between a potential causal factor and an observed effect are fulfilled in regard to the conclusion that moderate solarium use per se would increase melanoma risk Conclusion: Current scientific knowledge does not demonstrate a causal relationship between moderate solarium use and melanoma risk. Therefore, the debate is not closed.

A Critical Appraisal of the Recent Reports on Sunbeds from the European Commission's Scientific Committee on Health, Environmental and Emerging Risks and from the World Health Organization

The European Commission's Scientific Committee on Health, Environmental and Emerging Risks and the World Health Organization recently published reports which concluded that a large proportion of melanoma and non-melanoma skin cancer is attributable to sunbed use, and that there is no need to use sunbeds as there are no health benefits and they are not needed to achieve an optimal vitamin D level. The overall conclusion from both bodies was that there is no safe limit for UV irradiance from sunbeds. We are, however, deeply concerned that these assessments appear to be based on an incomplete, unbalanced and non-critical evaluation of the literature. Therefore, we rebut these conclusions by addressing the incomplete analysis of the adverse health effects of UV and sunbed exposure (what is 'safe'?) and the censored representation of beneficial effects, not only but especially from vitamin D production. The stance taken by both agencies is not sufficiently supported by the data and in particular, current scientific knowledge does not support the conclusion sunbed use increases melanoma risk.