Daily use of sunscreen may lower cancer risk later in life

The results from the follow-up period of the Nambour Trial by the Queensland Institute of Medical Research were announced at 11^th​ World Congress of Cancers of the Skin, last month. In the original Nambour trial, commencing in 1992, 1,621 residents were randomly divided between the treatment group (those asked to apply factor 16 sunscreen to head, neck, arms, and hands every morning) and a control group (those asked to continue with their usual discretionary sun care regime). On account of the study period the results inevitably concentrate on sunscreens that protect against UVB rays, as opposed to UVA and UVB combination products that were introduced into the market at a later date. Treatment continued over four and a half years and primary results suggested a decrease in squamous cell carcinomas (SCCs), those affecting the upper layers of skin and representing the second most common form of skin cancer. In contrast initial results did not find a decrease in the incidence of basal cell carcinomas (BCCs), the most common form of skin cancer. After the initial 4.5 years, treatment stopped and subjects were free to continue with their preferred personal sun care regime, however they continued to be monitored for a further 8 years. Follow-up monitoring included completing 6 monthly questionnaires with questions on sunscreen use and the amount of time spent outdoors, and reporting any subsequently diagnosed skin cancers to the trial investigators. After 8 years of trial follow-up SCC incidence (the number of persons affected) was reduced by 35 per cent in the former daily sunscreen treatment group, conversely, although there was a decline in BCC incidence the results were not significant. The study reports that most of the reduction in SCC incidence can be attributed to the daily sunscreen application during the trial period. However the effect was enhanced by the fact that some individuals in the intervention group continued to apply sunscreen more frequently than the control individuals during the follow-up period, attributable to a combination of personal choice and habit. Professor Green said the results are 'suggestive' of a reduction in BCC incidence telling Cosmetics Design that 'if the use of sunscreen had been randomised earlier in life than mid-adulthood (early-adulthood and childhood ideally) and BCC then monitored for longer, we might have seen an effect on BCC'​ adding however that for the moment this view is speculative. The Nambour study is a significant addition to research into skin care as there has been no other randomised controlled trial of sunscreen use to evaluate actual skin cancer prevention in humans. Furthermore, it is unlikely that a study of this kind will be repeated; as the study has suggested that daily sun care application does help to prevent SCCs it would be unethical to ask patients not to follow this line of recommended treatment. When asked whether she thought the research would spell good news for daily moisturisers containing SPF factors Green said that she didn't believe that the layer of moisturiser applied would be thick enough to provide the requisite protection. Incidentally this is also a problem with sunscreen application in general, with many studies suggesting that consumers do not benefit from the SPF factors stated on the label as not enough product is being applied.