People with pale skin and red hair may be more prone to developing a deadly form of skin cancer regardless of whether they spend time in the sun or not, a study said Wednesday.
Not only is this group more vulnerable to the sun's ultraviolet (UV) rays, but a study in mice has now shown that the pigment that gives hair a red hue may in itself have cancer-causing effects, said a paper in the journal Nature.
"We studied melanoma formation in 'redheaded' mice and discovered that the red pigment had an ability to promote melanoma formation, even in the absence of ultraviolet radiation exposure," co-author David Fisher, cancer centre director at Massachusetts General Hospital, told AFP.
"This was a surprising result for us, because we expected that fair skinned people get melanoma due to weak protection from sunlight and ultraviolet radiation.
"However the results suggest that even without UV exposure, the red pigment may contribute to melanoma formation" by damaging healthy cells.
Light-skinned redheads with freckles and an inability to tan have trouble producing the black-grown pigment eumelanin, which absorbs harmful UV rays -- instead producing the red-yellow pigment pheomelanin which provides a weak UV shield.
In lab studies using dark, red and albino mice, Fisher and a team discovered that melanoma occurred more frequently in the red mice than the other two groups, regardless of whether they were exposed to UV or not.
The study showed "that completely avoiding UV rays would not protect red-haired people from melanoma," United States cancer researchers Mizuho Fukunaga-Kalabis and Meenhard Herlyn wrote in a comment carried by Nature.
About 132,000 cases of melanoma, the deadliest form of skin cancer, are diagnosed each year and two to three million non-melanoma cancers, according to the World Health Organisation, which says the numbers rise every year.
Fukunaga-Kalabis and Herlyn said the findings begged the question: what can be done beyond sun protection to reduce melanoma risk in red-haired, fair-skinned people?
Research was needed, the pair said, into the drugs that may induce eumelanin production or boost cancer-protecting antioxidants.
"Moreover, red-haired individuals should undergo frequent dermatological skin checks, besides avoiding sun exposure."