A rare type of skin cancer that killed reggae star Bob Marley causes distinct genetic faults not driven by the action of sunlight, research has shown.
Acral melanoma most often affects the palms of the hands, soles of the feet, nail beds and other hairless areas of the skin.
Unlike more common forms of skin cancer, it is not triggered by the damaging effects of ultraviolet light.
Scientists at the University of Manchester analysed acral melanoma DNA from six patients and compared it with that from other types of skin cancer tumour.
They found clear differences in the type of DNA damage caused. In acral melanoma it was much more common to find that large chunks of DNA had broken off and re-attached in the wrong place. Other types of skin cancer were characterised by smaller DNA defects.
Study leader Professor Richard Marais, director of the Cancer Research UK Manchester Institute, said: "Too much UV radiation from the sun or sunbeds can lead to a build-up of DNA damage that increases skin cancer risk. But acral skin cancer is different because the gene faults that drive it aren't caused by UV damage. Pinpointing these faults is a major step towards understanding what causes this unique form of cancer, and how it can best be treated."
Nell Barrie, senior science information manager at Cancer Research UK, said: "We hope that understanding the faults that drive acral melanoma will unlock better ways of treating this rare yet aggressive type of skin cancer. Our scientists are striving to improve survival for all cancer patients, including those with rarer forms of the disease."