New research in mice suggests that redheaded people may be more susceptible to the dangerous type of skin cancer known as melanoma, even if they don't spend a lot of time in the sun.
The findings haven't been confirmed in humans. Still, researchers discovered that a genetic mutation that normally slightly boosts the risk of melanoma has a much greater effect in mice with reddish fur.
Should redheaded people panic or simply accept the higher risk?
Neither, said study author Dr David Fisher, chief of the department of dermatology at Massachusetts General Hospital in Boston. "We don't believe that this exonerates the sun in any way. People should be absolutely careful about sun exposure."
Hair evolved to protect skin
Pigmentation - the colour of skin and hair - probably evolved to protect animals from the damage of ultraviolet radiation from the sun, Fisher pointed out. Fairer pigments probably helped humans survive in higher and lower latitudes, where the threat of sun exposure isn't as high, he explained.
But now, people of different skin pigments are dispersed around the globe, and fairer-haired people live in places where they get lots of sun exposure.
In the new study, researchers tinkered with the genetic makeup of mice, giving them a mutant form of a gene that boosts the risk of melanoma. None of the mice were exposed to any ultraviolet radiation, to remove the effect of exposure. The researchers wanted to see if the added risk differed, depending solely on their fur colour.
About 10%of mice without red fur developed melanoma, and it took months, Fisher said. By contrast, at least 50%of the red-furred mice with the genetic mutation developed the skin cancer, and it took much less time for that to happen.
In contrast, albino mice with the genetic mutation didn't develop melanoma at all, he said. That suggests that something about pigmentation - the type that creates red fur in mice in particular -- makes mice more susceptible to melanoma if they have a certain kind of genetic makeup.
What the findings mean
What's going on? Fisher speculated that the increased risk of melanoma - in red-furred mice that had the genetic mutation but didn't get sun exposure - is related to the way the body creates pigmentation. The process may boost the risk of cancer, he said.
If the research is confirmed in humans, it would suggest that "for people who are careful about sun exposure, careful about using sunscreen and so on, that may not be enough," he said. As a result, it's even more vital to pay attention to changes in your skin, he stressed.
Fabian Filipp, an assistant professor of systems biology and cancer metabolism at University of California, Merced, said the study results are "an important avenue" to finding new ways to treat and diagnose melanomas. Filipp agreed with Fisher about the message of the study: "people with red hair and fair skin color have to be doubly careful."
The study appeared in the journal Nature.
Experts note that results from animal research are not always replicated in humans.
All about melanoma
For more about melanoma and other skin cancers, try the U.S. National Cancer Institute.
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