Sun exposure, sunbeds and sunscreens and melanoma. What are the controversies?

The association between various measures of sun exposure and melanoma risk is quite complex to dissect as many case-control studies of melanoma included different subtypes of melanomas which are likely to be biologically different, so interpretation of the data is difficult. Screening bias in countries with high levels of sun exposure is also an issue. Now that progress is being made in the genetic subclassification of melanoma tumours, it is apparent that melanomas have different somatic changes according to body sites/histological subtypes and that UV exposure may be relevant for some but not all types of melanomas. Melanoma behaviour also points to non-sun-related risk factors, and complex gene-environment interactions are likely. As UV exposure is the only environmental factor ever linked to melanoma, it is still prudent to avoid excessive sun exposure and sunburn especially in poor tanners. However, the impact of strict sun avoidance, which should not be recommended, may take years to be apparent as vitamin D deficiency is a now a common health issue in Caucasian populations, with a significant impact on health in general.