SUNLIGHT - A MAJOR FACTOR ASSOCIATED WITH THE DEVELOPMENT OF MELANOCYTIC NEVI IN AUSTRALIAN SCHOOLCHILDREN

Background: Case-control studies have identified melanocytic nevi (MN) as the most important phenotypic risk factor far melanoma. A knowledg e of any environmental factors that cause MN may facilitate prevention of melanoma. Objective: This study was undertaken to explore the poss ible role of ambient solar irradiation in the development of MN in chi ldren. Methods: With a standard protocol developed after international consultation, the same medical observers examined children in three A ustralian cities (Melbourne, Sydney, and Townsville) that span a wide range of latitude. Results: A total of 1123 Australian schoolchildren 6, 9, 12, and 15 years of age were surveyed. Larger numbers of MN were found (mean 65.4 MN, standard deviation 52.9) than in pre vious studi es of children. Prevalence increased with diminishing latitude (51.1 i n Melbourne, 66.5 in Sydney and 77.2 in Townsville), particularly in c hildren 6 and 9 years of age. Although nevus numbers were higher in ch ildren with light skin and hair, blue eyes, and freckling, the latitud e gradient remained after adjustment for these and other factors in mu ltivariate analysis. Conclusion: Latitude of residence, and by implica tion ambient UV radiation, is strongly related to nevus prevalence in young Australian children. However, these differences diminish with ag e and may disappear by 15 years of age.