AURORA, Colo. (Feb. 5, 2009) – Taking young Caucasian children to the beach for vacation may increase their chances of getting the deadly skin cancer melanoma, a study of more than 600 Colorado kids reveals.
Researchers led by Lori Crane, PhD, MPH, of the Colorado School of Public Health used interviews and physical examinations to see if exposure to ultra-violet rays caused the children to develop more moles, because the total number of moles on a child’s body represents a risk factor for melanoma later in life.
The children in the Colorado study had “5 percent more moles for each vacation at the waterside,” Crane reported. “Understanding the development of moles is important to understanding the development of melanoma.”
Most moles develop in childhood, Crane said. They are almost always benign and result from a mixture of genetics and environment. But there is a strong relationship between the number of benign moles and the development of melanoma.
So the results of Crane’s research have major public health implications. Melanoma kills roughly 8,000 people a year, according to the American Cancer Society. The cancer society estimates about 59,000 new diagnoses of melanoma each year. Caucasians are especially susceptible.
Because they live at a higher altitude and much sunnier climate than many Americans, Coloradans receive more sun exposure. That exposure is born out in skin cancer rates that Crane said are 20 percent higher than the national average.
Interestingly, however, it was trips to oceanside, riverside and lakefront vacations (mostly out of state) that resulted in a higher number of moles among the children in the study.
“If you go to Breckenridge,” Crane explained, “even though the sun is intense, you’re not going to get as much ultra-violet (UV) exposure as you would at a beach or lake because you typically wear a lot of clothes in the mountains.”
Researchers did place some limits on what qualified as a “waterside vacation.” For oceans, rivers and lakes in areas north of a line described by latitude 27.5 degrees North, only summer vacations counted as adding UV exposure. Waterside vacations to areas south of latitude 27.5 degrees North counted year-round as adding UV exposure.
At the beach, it doesn’t seem to matter how long you stay or even if you slather your kids in sunscreen; children still show increased numbers of moles, Crane and her colleagues from the public health school, the University of Colorado Denver School of Medicine Departments of Dermatology and Pediatrics, the Kaiser Foundation Health Plan of Colorado and the Dermatology Department at the Denver Veterans Administration Hospital found. Waterside vacations taken less than a year before physical examinations did not appear to result in increased numbers of moles. This suggested to researchers that it may take a year or more before the effects of UV exposure can be seen in mole development. Alternatively, it may be that children become more resistant to the mole-producing effects of sun exposure as they age.
“An interesting and potentially important finding is that the number of days spent on waterside vacations and the total (ultra-violet dose) on those vacations appeared to have no significant effect on nevus (mole) count, whereas the occurrence of the vacation had an effect,” the researchers wrote in the journal Cancer Epidemiology, Biomarkers & Prevention. “We offer an interpretation that a threshold of UV exposure is received relatively early during vacations of this nature; thus, vacations of, for example, 3 days are equivalent to vacations of 10 days in terms of their effect on nevus (mole) development.”
The ability to go on more waterside vacations might actually put the children of affluent people at greater risk of developing melanoma later in life, the authors speculate.
While covering up exposed skin with clothing, staying out of the midday sun and using sunscreen are all good habits, deterrents may not be foolproof. Sunscreen is no panacea, said Crane, an associate professor and chair of the public health school’s Department of Community and Behavioral Health. “The only evidence that sunscreen prevents skin cancer is for squamous cell skin cancer,” not melanoma. “Further, since sunscreen is very effective in preventing sunburns, it encourages individuals to stay outside for extended periods of time in intense sunshine, which may ultimately increase their risk of skin cancer.”
Crane is now searching for funding to continue her study of the Colorado children, who were born in 1998 and have lived in Colorado their entire lives. Comprehensive skin exams took place in 2005, when the children were seven. Crane also has skin exam data for 2006, 2007 and 2008. But she said it is critical to follow the group as long as possible to more fully grasp the relationship between sun exposure, mole development and melanoma.
The School of Medicine faculty work to advance science and improve care as the physicians, educators and scientists at University of Colorado Hospital, The Children’s Hospital, Denver Health, National Jewish Health, and the Denver Veterans Affairs Medical Center. Degrees offered by the UC Denver School of Medicine include doctor of medicine, doctor of physical therapy, and masters of physician assistant studies. The School is part of the University of Colorado Denver, one of three campuses in the University of Colorado system. For additional news and information, please visit the UC Denver newsroom online.
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