The most dangerous skin cancers are melanomas, which comprise about 5 per cent of skin cancers. Melanomas can be treated successfully when diagnosed early. They are noticed as new spots, or a change to an existing freckle or mole so that it increases in size, or alters in shape or colour.
Melanomas have an irregular edge or surface, are blotchy and may be brown, black, blue, red, white or light grey. Melanomas may itch or bleed, and the changes are usually noticed over several weeks or a few months – not in a few days.