Causes and risk factors of skin cancer
The main cause of most skin cancers is sun exposure. But other things can increase the risk. These are called risk factors. Having one or more risk factor does not mean you will get skin cancer. Having no risk factors does not mean you will not develop skin cancer. Risk factors may include the following.
Ultraviolet (UV) light from the sun is the main cause of most skin cancers. UV light damages the DNA (genetic material) in our skin cells and can cause skin cancer.
Exposure at a young age
Being exposed to too much sun or getting sunburnt as a child are important risk factors for developing basal cell carcinomas (BCCs) or squamous cell carcinoma (SCCs). It is likely that skin damage from UV light during childhood will not show up until many years later.
Exposure to sun over time
Skin cancer is more common than it used to be. This is because people are living longer, so their exposure to the sun over their lifetime is greater. Sun exposure over a long time can cause both types of skin cancer. But it is more strongly linked with developing an SCC.
People who work outdoors for a living, such as farm workers, builders and gardeners, are more at risk of developing skin cancer. This is because they are often exposed to the sun for long periods of time.
Skin cancer will usually show up later in life. It often happens after the age of 40, but it is more common in older age. However, the number of younger people developing skin cancer is also rising.
People with pale skin who tend to go red or freckle in the sun will be most at risk. Children and young adults who have been over-exposed to the sun have an increased risk of developing some forms of skin cancer, especially if they have pale skin.
People with darker or black skin have a very low risk of getting basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs). This is because they have a pigment in their skin called melanin, which gives them protection. But although the risk is much lower, they can still get BCCs and SCCs.
Actinic keratosis (AK), also called solar keratosis, is a crusty skin growth caused by damage from exposure to UV light.
Usually, AK affects mainly the face, scalp and hands. If left untreated for many years, AK may sometimes develop into SCC.
Using sunbeds and sunlamps increases the risk of developing some skin cancers. The risk increases the more you use a sunbed or sunlamp. It also increases if you were young when you started using them.
If you have had a skin cancer before, you are 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.
People who have a weakened immune system have a higher risk of developing skin cancer. For example:
- people who take drugs that lower their immunity (immunosuppressants) after a transplant of an organ, such as a kidney
- people who have HIV
- people with some types of blood cancer, such as chronic lymphocytic leukaemia (CLL).
People with a weakened immune system are more likely to develop SCCs. But BCCs and melanomas are also more common in them than in the general population.
If you need to take drugs to suppress your immune system, the benefit of this outweighs the potential risk of developing skin cancer. However, it is important that you see your doctor regularly to check for early signs of skin cancer.
Another possible rare cause for non-melanoma skin cancer is overexposure to certain chemicals, usually 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.
Most skin cancers are not caused by an inherited faulty gene that can be passed on to other family members. But, families are likely to have the same skin type, which may increase their risk of developing a skin cancer.
People with certain rare inherited conditions, such as Gorlin syndrome or xeroderma pigmentosum (XP), have a higher risk of developing skin cancer.
Below is a sample of the sources used in our skin cancer information. If you would like more information about the sources we use, please contact us at firstname.lastname@example.org
Motley et al. British Association of Dermatologists. Management of the patient with primary cutaneous squamous cell carcinoma. 2009.
National Institute for Health and Care Excellence (NICE). NG12: Suspected cancer: recognition and referral. 2015 (updated 2017).
National Institute for Health and Care Excellence (NICE). NG134: Sunlight Exposure: Benefits and Risks. 2016.
National Institute for Health and Care Excellence (NICE). PH32: Skin Cancer Prevention. 2011 (updated 2016).
Scottish Intercollegiate Guidelines Network (SIGN) 140. Management of primary cutaneous squamous cell carcinoma. 2014.
Telfar N et al. Guidelines for the management of basal cell carcinoma. British Journal of Haematology. 2008.
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor James Larkin, Consultant Medical Oncologist.
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