Risk factors and causes of skin cancer
Ultraviolet (UV) light (UVA and UVB) from the sun is the main environmental cause of most skin cancers.
UV light damages skin cells and can cause skin cancer. Episodes of overexposure to the sun or sunburn in childhood are important risk factors in the development of basal cell cancers. It’s likely that skin damage from UV light that occurs in childhood doesn’t show up until many years later. Sun exposure over a lifetime is more significant for squamous cell cancers.
Skin cancer is more common than it used to be and there are several possible reasons for this. People are living longer so their lifetime sun exposure is greater. They often spend more time enjoying outdoor activities and holidays in sunny climates, and many people still consider suntans to be healthy and attractive. There’s also been an increase in skin cancer awareness in recent years.
People who work outdoors for a living, such as farm workers, builders and gardeners, are at an increased risk of developing skin cancer because of prolonged exposure to the sun. This is relevant for both squamous cell and basal cell cancers.
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, especially if they have fair skin. This will not show up until later on in life – usually after the age of 40, and often not until the age of 60 or 70. Black- or brown-skinned people have an extremely low risk of developing skin cancer because the pigment melanin in their skin gives them protection.
The regular use of sunlamps and sunbeds can increase the risk of developing some skin cancers. This is seen mainly in people who have used them excessively for many years.
If you’ve previously had a skin cancer, you’re at risk of developing another one, either in the same place as before or somewhere else on your body.
Previous radiotherapy treatment
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Previous radiotherapy treatment for other conditions can sometimes cause skin cancer (particularly basal cell carcinoma) in the treatment area later in life.
People who have to take drugs that lower their immunity (immunosuppressants) – for example, after a kidney transplant – are at an increased risk of getting skin cancer. Squamous cell cancers are the most frequent, but basal cell cancers and melanomas are also more common in these people than in the general population.
However, the reason for taking the immunosuppressants outweighs the potential risk of skin cancer. If you’ve had a transplant it’s important that you see your doctor regularly to check for early signs of skin cancer.
Another rare possible cause for non-melanoma skin cancer is overexposure to certain chemicals at work. These include:
You should wear protective clothing if you frequently handle these substances. Very small amounts of these chemicals used in the home are unlikely to cause skin cancer, but you should always follow the manufacturer’s instructions when using them.
Most skin cancers are not caused by an inherited faulty gene that can be passed on to other family members. However, families are likely to have the same skin type, which may increase their risk of developing a skin cancer.
People with certain rare hereditary conditions, such as Gorlin syndrome or xeroderma pigmentosum (XP), have a higher risk of developing skin cancer.