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Causes of skin cancerUltraviolet light from the sun is the main cause of skin cancer. Skin cancer is becoming more common and there are several possible reasons for this. People are living longer (and so their lifetime sun exposure is greater). They often have more time and money for outdoor recreation and holidays in sunny climates and many people still consider suntans to be healthy and attractive. It is likely that most skin damage from ultraviolet radiation occurs before the age of 20. It is thought that a build-up of overexposure to the sun over a period of several years can lead to the development of basal cell and squamous cell skin cancers.Black- or brown-skinned people have a very low risk of developing skin cancer because the melanin pigment in their skin gives them protection. A fair-skinned person who tends to go red or freckle in the sun will be most at risk. Children and young adults who have been overexposed to the sun have an increased risk of developing some form of skin cancer. This will not show up until later on in life – usually after about age 40, and often not until the 60s or 70s.The regular use of sunlamps and sunbeds increases the risk of developing skin cancer.Areas of skin that have been badly burned, or have long-term inflammation have an increased risk of squamous cell carcinoma.Radiotherapy given to treat other conditions can sometimes cause skin cancers in the treatment area later in life.People who have to take drugs which lower their immunity (immunosupressants) – for example, after a kidney transplant – are also at increased risk of getting skin cancer.Other rare possible causes are overexposure to certain chemicals at work, including coal tar, soot, pitch, asphalt, creosotes, paraffin waxes, petroleum derivatives, hair dyes, cutting oils and arsenic. You should wear protective clothing if you are handling these substances frequently.Some people with rare hereditary conditions have a higher risk of developing skin cancer. However, non-melanoma skin cancers are not caused by inherited faulty genes that can be passed on to other family members and so other members of your family are not at a higher risk of developing skin cancer.What are the symptoms?Both basal cell and squamous cell carcinomas can appear in a variety of forms.Basal cell cancers can develop as a small lump on your skin which is smooth and pearly or waxy in appearance. It may bleed sometimes or develop a crust. It may begin to show signs of healing and yet never quite does. Instead, you may see a flat, red spot, which is scaly and crusty. Sometimes there is just a firm, red lump. Skin cancers are usually painless and grow slowly. They can appear anywhere on your body but are most likely to occur on exposed skin, especially your face.Squamous cell carcinomas often have a scaly appearance. Sometimes they have a hard, horny cap and can feel tender to touch. They are also found on the face, bald scalps, arms, backs of hands and lower legs.If you notice anything unusual on your skin which does not go away within a month, you should show it to your doctor. There are, however, many other conditions that may appear in the skin which are not cancer, particularly among older people. You may still wish to have these treated for cosmetic reasons.Signs and symptoms of non-melanoma skin cancer:Most likely to appear on face, neck or other exposed skin.