THE STUDY highlighted in this issue of the ARCHIVES1 indicates yet again the great potential value of cutaneous sunscreen application, when undertaken conscientiously and carefully, against the now extremely well-documented ravages of sunlight in both the short and long term. This splendid randomized controlled trial is the continuation of a previous one showing sunscreen efficacy against the development of squamous cell carcinoma.2 It provides further evidence in a very large number of adults (1621 subjects aged 25-74 years), over a reasonably long time (2½ years), in a very ultraviolet (UV)-intense environment (Queensland, Australia), that frequent, liberal applications of high-protection sunscreen by ordinary people under normal circumstances is 25% more efficient against the development of potentially premalignant actinic keratoses than ad hoc applications. Less difference was seen over the subsequent and final 2 years of the study, arguably because of increased care in applying sunscreen regularly in the control group as the trial progressed. This is a great relief to us dermatologists because it proves that we are not advising our patients incorrectly; but it also clearly shows that participants in the control arm of the trial, who were using sunscreens just as most of us do, did not fare as well as their counterparts in the study group. So why not? Well, because sunscreens should be used in the context discussed below.
Hawk JLM. Cutaneous Photoprotection. Arch Dermatol. 2003;139(4):527-530. doi:10.1001/archderm.139.4.527