Early life sun exposure, from birth to 20 years old, may specifically increase the risk of melanomas with BRAF gene mutations. Skin cancers often contain different gene mutations, butjust how these mutations contribute to the cause of melanomas has been amystery.
A new clue comes from scientists at the University of North Carolina atChapel Hill Schools of Medicine and Public Health. Their researchindicates that early life sun exposure, from birth to 20 years old, mayspecifically increase the risk of melanomas with BRAF gene mutations. Adifferent mutation, on the NRAS gene, was found in patients who had sunexposure later in life (between ages 50 to 60 years old). The resultsindicate that different subtypes of melanoma are associated withdifferent risk factors
“The findings suggest that melanoma subtypes have different causes. Thisis important for learning more about how to prevent and treat skincancer,” said Dr. Nancy Thomas, associate professor of dermatology inthe UNC School of Medicine, a member of the UNC Lineberger ComprehensiveCancer Center and lead author of the study. This finding is expected tostrengthen current recommendations to protect children from sun exposurein order to prevent melanoma, Thomas said.
The study, published in the May 2007 edition of the journal CancerEpidemiology Biomarkers and Prevention, presents some of the first datato link early life sunlight exposure to a specific mutation inmelanomas.
Researchers interviewed 214 melanoma patients in North Carolina abouttheir risk factors for melanoma and about the various places they hadlived. Each patient’s UV sun exposure was estimated from theirresidential history and satellite-base measurements. DNA from thepatients’ melanomas was then analyzed for mutations.
Patients with melanomas that contained the BRAF mutation, found in abouthalf of all melanomas, were more likely to report high levels of sunexposure before age 20. People with the NRAS mutation were more likelyto have had high exposure between the ages of 50 and 60. About 15percent of melanomas contain the NRAS mutation.
The findings come from the initial phase of an ongoing study that willultimately include more than 1,000 patients from the U.S. and Australia.The research was funded by the Dermatology Foundation, the NationalCancer Institute and the UNC Lineberger Cancer Center.