For young children, a family history of frequent, sun-splashed vacations is associated with more nevi, and nevi counts are a reliable indicator of lifetime skin cancer risk.
In fact for kids under the age of 7 each waterside vacation bumps the small nevi count by 5%, according to Lori Crane and colleagues at the University of Colorado.
In 2005, Crane and colleagues examined 681 children that were born in 1998 and lived continuously in Colorado. They also interviewed parents each year between 2003 and 2005 regarding vacations, sun exposure, and the use of sun block and hats.
The scientists classified vacations as waterside or not after asking about recreational activities like boating, surfing and water skiing.
They also accounted for climate and time of the year when vacations took place. Hawaii vacations counted as waterside no matter when they took place for example, but coastal North Carolina getaways counted as waterside only during summer.
No word on whether demerits were given to sun seekers venturing to Boston, by the way.
Their findings appear in Cancer Epidemiology, Biomarkers and Prevention.
“Parents should be aware of the effect that vacations may have on their children’s risk for developing melanoma as adults and they should be cautious about selection of vacation locations,” wrote the scientists.
Interestingly, use of sunscreens and hats did not impact risk of developing small nevi, nor did eye color. And neither vacation length nor total estimated UV exposure predicted nevus counts; it was just the number of vacations.
Crane’s team suggested a threshold phenomenon could explain these observations. According to this hypothesis, radiation necessary to trigger nevus formation is obtained early during the vacation and additional exposure has no impact.
Boys were found to be at greater risk for sun-driven nevi development. They accumulated19% more by age 7 than girls. And Hispanic ethnicity reduced the risk of nevi by 35% versus Caucasians.
The presence of facial freckles and a positive sunburn history were also associated with more nevi.