A longitudinal study established a link between different ultraviolet (UV) exposure measures in children, such as the number of waterside vacations or sunburns, and biomarkers of melanoma risk, such as the number of freckles or moles that develop during childhood, according to data published in Cancer Epidemiology, Biomarkers & Prevention.

“Early-life UV exposure that confers risk for melanoma also plays a role in development of moles or melanocytic nevi, which can be both a biomarker for melanoma risk and occasionally an immediate precursor,” said Neil Box, PhD, assistant professor in the Department of Dermatology at the University of Colorado in Denver.

The study showed that children with certain combinations of the blue eye-colour gene variant and genetic variants that cause red hair are particularly susceptible to the formation of freckles and moles as they take waterside vacations early in life.

“Our research demonstrates that longitudinal studies are a powerful way to find and characterise gene-environment interactions,” Box said.

“These findings are an important step toward identifying high-risk groups for melanoma based on genotype and sun exposure history.

“Our data could potentially help produce refined guidelines or recommendations for UV exposure behaviours in genetically high-risk children,” Box added.

Box and colleagues used DNA samples and information about sun-behavioural patterns from 477 non-Hispanic or Hispanic white children to evaluate the effect of different levels of sun exposure on mole and freckle formation in relation to genetic factors known to be associated with melanoma.

Following the children’s behaviour from 2004 to 2008, the researchers discovered that the number of moles and freckle density increased among the children in each successive year.

Additionally, total number of sunburns, waterside vacations, and chronic sun exposure increased each year.

All of the measures of sun exposure contributed to increased freckle counts, and cumulative chronic UV exposure was a major driver of freckle development.

“We also found that children who are homozygous for the major blue eye-colour gene variant are particularly susceptible to formation of moles as they take more waterside vacations in early life,” Box said.

“Those kids with certain combinations of the blue eye-colour variant and genetic variants that cause red hair colour were also more likely to have larger moles as they sustained more sunburns.”

The study also demonstrated for the first time that children who have particular red hair colour gene variants display significantly more freckles as they experience more waterside vacations.

According to Box, the results of this study start to identify specific behaviours that can be changed in children who are at high risk for melanoma in later life.

Source: AACR