Causes and risk factors of skin cancer

Most skin cancers are caused by exposure to the sun. This may be long-term exposure or short periods of overexposure. This is because ultraviolet (UV) light from the sun damages the DNA (genetic material) in our skin cells.

There are two main types of skin cancer: basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). People with a history of sunburn or overexposure to the sun in childhood have a greater risk of developing BBC. This won’t usually show up until many years later. Sun exposure over your lifetime is more significant in developing SCC.

People who work outdoors have a greater risk of skin cancer as they are exposed to the sun for long periods of time. Fair-skinned people have a greater risk than black- or brown-skinned people. This is because the pigment in darker skin gives protection.

Regularly using sunbeds and sunlamps can also increase the risk of developing some skin cancers.

Other risk factors include previous skin cancers, previous radiotherapy treatment, lowered immunity, overexposure to chemicals at work and rare genetic conditions.

Sun exposure

Ultraviolet (UV) light from the sun is the main environmental cause of most skin cancers. UV light damages the DNA (genetic material) in our skin cells and can cause skin cancer.

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 during childhood doesn’t show up until many years later

Skin cancer is more common than it used to be. This is because people are living longer so their lifetime sun exposure is greater. Sun exposure over a lifetime is more significant for squamous cell cancers.

People who work outdoors for a living, such as farm workers, builders and gardeners, are at an increased risk of developing skin cancer because they are often exposed to the sun for long periods of time. 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.


Reguarly using sunlamps and sunbeds can increase the risk of developing some skin cancers. The more you use a sunbed or sunlamp, and the earlier in life you begin using them, the greater your risk.

Previous skin cancers

If you’ve had a skin cancer before, you’re at risk of getting another one. This could be either in the same place as before (a local recurrence) or somewhere else on your body.

Previous radiotherapy treatment

Previous radiotherapy treatment for other conditions can sometimes cause skin cancer (particularly basal cell carcinoma) in the treatment area, later in life.

Lowered immunity

People who take drugs that lower their immunity (immunosuppressants) – for example, after a kidney transplant – are at an increased risk of skin cancer. Squamous cell cancers are the most common, 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 developing 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.

Exposure to chemicals

Another rare possible cause for non-melanoma skin cancer is overexposure to certain chemicals at work. If you may be at risk from chemicals in the workplace, you should wear protective clothing and use protective equipment. Always follow the manufacturer’s instructions when using chemicals at home.

Genetic conditions

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.