Background: Meta-analyses of observational case-control studies have demonstrated no association between sunscreen use and the development of malignant melanoma.
Objectives: To examine whether this observation is to be expected given the period during which the case-control studies were conducted, the sunscreens prevalent at that time, and how sunscreen is used and applied in practice. To predict whether modern sunscreens are likely to be effective as a preventative agent in melanoma.
Methods: The protection against solar ultraviolet radiation delivered by sunscreens available prior to the early 1990s (when the data used in most published case-control studies were collected) was estimated by combining their absorption properties with the amount applied in a way reflecting common usage. Similar estimates were made for the protection offered by modern sunscreens.
Results: It is not surprising that case-control studies have failed to find any association between sunscreen use and the risk of melanoma when consideration is given to the sunscreens in common usage at the time and the way in which sunscreen is applied in practice. Modern high Sun Protection Factor, broad-spectrum sunscreens, on the other hand, can be expected to be an effective measure in helping to prevent melanoma compared with sunscreens typical of those used 10-20 years ago.
Conclusions: It is reasonable to suppose that the improvement in performance of modern sunscreens will lead to a worthwhile benefit as a preventative agent against melanoma, although these benefits may not be seen for several decades.