The evidence on the efficacy of sun avoidance and use of protective clothing for the prevention of melanoma is complex, but overall supports the hypothesis that intermittent sunburn in childhood is a preventable risk factor. There are no data from randomized trials linking sun avoidance and use of protective clothing to a reduced cancer incidence. Evidence to support avoiding artificial tanning devices is still weak.
There is good evidence from 1 trial for a modest benefit of sunscreen in preventing squamous cell cancer. Based on this randomized trial, 140 people would need to use daily sunscreen for 4 1/2 years to prevent 1 squamous cell cancer. In another trial, sunscreen use led to the development of fewer nevi, but the study had substantial flaws and the users still had many new nevi, making the clinical significance of this finding unclear. In a meta-analysis of population-based case-control studies, sunscreen use was not associated with an increased risk for melanoma, and in one randomized trial use of sunscreen with a high SPF was associated with an increased incidence of sunburn because users were overconfident about the degree of protection.
There is good evidence from 1 trial for the effectiveness of counseling by a physician in the context of a broader, community-based educational intervention. The specific contribution of the office-based component to the overall effectiveness of the intervention was not described.