New route to skin cancer in red-haired people uncovered
Thursday 1 November 2012
The increased risk of developing skin cancer in people with red hair and fair skin may be down to more than a lack of natural protection against ultraviolet (UV) radiation, an American study has found.
In fact, the type of skin pigment predominantly found in red-haired, fair-skinned individuals may itself contribute to the development of melanoma, the most serious form of skin cancer, according to research published in Nature.
But experts were keen to highlight the continued importance of staying safe in the sun, as the vast majority of skin cancers are caused by overexposure to UV radiation from the sun, or from sunbeds.
Our skin contains several types of the pigment melanin. One of these is called eumelanin, a dark brown or black form predominant in individuals with dark hair or skin.
But a lighter blond-to-red pigment called pheomelanin is predominant among those with red hair, freckles and pale skin.
While research has proved that red/blond melanin is less effective at mitigating against the effects of UV damage, a minority of fair-skinned people develop melanomas that can't be explained by their being relatively unprotected against UV radiation.
Researchers at Massachusetts General Hospital (MGH) have discovered one such non-UV-related route to melanoma.
The team looked for additional contributors to melanoma development in mice that were almost genetically identical except for the gene that controls the type of melanin produced.
One group of dark-coloured mice had the typical variant leading to a predominance of dark melanin, while another had the red-blonde type.
Researchers activated the melanoma-associated cancer gene in patches of the animals' skin, expecting that no melanomas would form without additional environmental stresses like exposure to UV radiation.
To their surprise they found that within months half of the mice with the redhead pigment had developed melanomas, compared to only a handful of the mice with the darker melanin.
A third group of mice that were incapable of producing any pigment, known as "albino redheads", didn't develop melanoma in the absence of UV radiation, leading researchers to conclude that the red-blond pigment could itself be a cause of melanoma.
Professor Julia Newton-Bishop, from the Cancer Research UK Centre at the University of Leeds, said: "This is a very interesting finding and contributes to our understanding of why red-headed, freckly people are particularly prone to skin cancer.
"There's no doubt that the majority of melanomas are caused by UV radiation from the sun - and protecting your skin in the sun is crucial - but this work suggests that there may be other paths to melanoma in red-haired, freckly people."
She also said that the work further emphasises that fair-skinned people with freckles should keep an eye out for any new moles or blemishes on their skin or any changes to existing ones.
Dr David Fisher, chief of the MGH Department of Dermatology, said: "Right now we're excited to have a new clue to help better understand this mystery behind melanoma, which we have always hoped could be a preventable disease."
He added: "The risk for people with this skin type has not changed, but now we know that blocking UV radiation - which continues to be essential - may not be enough.
"It will be important for these individuals to be aware of changes in their skin and never hesitate to have something checked by a dermatologist, even if they have scrupulously protected themselves from sun exposure, which we continue to encourage."
Dr Fisher said that around six out of seven melanomas are treatable if discovered early, adding that the new discoveries could help pave the way for more effective sunscreens.
Cancer Research UK's Professor Newton-Bishop predicted that the research could lead to new ways to prevent melanoma in people with genetic faults that increase their risk of the disease.
Copyright Press Association 2012
- Mitra, D. et al. An ultraviolet-radiation-independent pathway to melanoma carcinogenesis in the red hair/fair skin background. Nature doi:10.1038/nature11624
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