Melanoma may be preventable by regular use of sunscreen, finds an Australian study published in the Journal of Clinical Oncology.  The study of more than 1,600 adults showed that regular use of sun screen led to a 50% decrease in melanoma and 73% decrease in invasive melanoma.

Despite the known role of sun exposure in melanoma, the use of sun screen for prevention has been considered controversial. The only evidence comes from a randomized trial of sun screen application in Canadian children, conducted between 1993 to 1996 that showed a small reduction in new melanocytic nevi (considered to be predictors of melanoma) in children randomised to sunscreen.

Adele Green and colleagues from the University of Queensland undertook a community based trial looking at use of sunscreen on the incidence of basal and squamous cell carcinoma. The current publication reports on their examination of melanoma as a secondary trial end point.

In 1992, 1,621 randomly selected white residents from Nambour (Queensland, Australia), aged between 25 and 75 years, were randomly assigned to sun screen intervention (where they were given a free unlimited supply of a broad spectrum sun screen of SPF 16 and instructed to use it daily on their head, neck, arms and hands, n= 812) or the comparator arm (who continued using sunscreen of any SPF at their own discretion, n=809).

Results showed ten years after the trial stopped, 11 new primary melanomas were observed in the daily sunscreen group versus 22 in the discretionary group (HR 0.50, 95% CI, 0.24 to 1.02; P=.051). For invasive melanoma the differences were even greater - 3 cases occurred in the daily sunscreen group versus 11 in the discretionary group (HR 0.27; 95% CI, 0.08 to 0.97).

Furthermore, the investigators found that melanoma incidence was decreased at all sites of the body, not just those assigned to protection by sunscreen.

“Our findings provide reassurance in view of the widespread uncertainty to date about sunscreen’s ability to prevent melanoma,” conclude the authors, adding that the study should be considered relevant both for white people living in sun climates like Australia, and those living in temperate climates in North America and Europe.

Given the importance of early-life sun exposure in the genesis of melanoma, the authors add, long-term sunscreen intervention among children and adolescents may yield even greater benefits in cancer prevention.

Reference

A Green, G Williams, V Logan et al. Reduced Melanoma After Regular Sunscreen Use: Randomised Trial follow-up. J Clin Oncol 2010,  29:257-263.