Normal melanocytes are found in the basal layer of the epidermis – the bottom part of the outer layer of the skin. The melanocytes produce a protein called melanin, which protects the skin by absorbing ultra violet (UV) radiation. Melanocytes are found in equal numbers in dark and white skin types but the melanocytes in dark skin produce much more melanin. People with dark brown or black skin are very much less likely to be damaged by UV radiation than those with white skin.

Non-cancerous growth of melanocytes causes common lesions like freckles and moles, whereas cancerous growth causes melanoma. There are different types of melanoma and if picked up early enough, melanoma can be cured.

The cause of skin cancer, like other forms of cancer, is not completely known. Excessive exposure to sunlight is the single most important factor associated with the development of skin cancers. Consequently, skin cancers most commonly develop on the face and the arms, the most sun-exposed parts of the body.

• Sun exposure – Sunburns, especially in childhood, have been linked closely with basal cell carinoma, whereas cumulative sun exposure over many years is associated with the development of squamous cell carcinoma. The role of sunlight exposure in melanoma is less clear.
• Genetics – Genetic predisposition for the occurrence of malignant melanoma is perhaps the most important risk factor. Individuals with fair hair (red or blonde), pale eyes (green or blue) and fair skin are at high risk of skin cancer.
• Other possible causes – Other possible causes of skin cancer include X-rays, trauma, viruses, infection, smoking and certain chemicals.