Causes and risk factors of skin cancer
Most skin cancers are associated with over-exposure to the sun. But other factors can increase your risk as well.
There are certain things that can increase the chance of developing skin cancer. These are called risk factors. Having one or more risk factors does not mean you will get skin cancer. And not having risk factors does not mean you will not develop it.
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.
Skin damage can occur due to exposure to the sun over a long period of time, or to being exposed to too much sun and getting sunburnt.
Over-exposure to sun at a young age
People with a history of sunburn or overexposure to the sun in childhood and young adulthood have a greater risk of developing basal cell carcinomas (BCC) or squamous cell carcinoma (SCC), or melanoma. Skin damage caused in childhood will not usually appear until many years later.
Exposure to sun over time
Because we are living longer, we are exposed to more sun during our lifetime. This means skin cancer is more common than it used to be. Skin cancer is more common in people over the age of 40 and becomes more common with age. But the number of younger people developing skin cancer is also rising.
People who work outdoors – for example, farm workers, builders and gardeners – have a greater risk. This is because they are exposed to the sun for long periods of time.
All types of skin are at risk of sun damage and skin cancer. But skin cancer is more common in fair-skinned people, who tend to burn easily or go red or freckle in the sun and whose skin does not tan. This is because they have less melanin. This is the protective layer in the skin.
People with darker skin or black skin have a lower risk of developing BCC or SCC. This is because they have more melanin in their skin. However, they are still at risk – particularly of getting a skin cancer where the body has less, or no direct sun exposure.
Actinic keratosis (AK) is also called solar keratosis. It is a crusty skin growth caused by damage from exposure to UV light.
AK affects mainly the face, scalp and hands. If left untreated, it may develop into SCC of the skin.
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 more at risk of getting another one. This could be in the same place as before (a local recurrence). Or it could develop somewhere else on your body.
Bowen’s disease is sometimes called squamous cell carcinoma in situ. It is a very early form of slow-growing skin cancer. It is caused by the growth of cancerous cells in the outer layer of the skin (epidermis). If left untreated, Bowen’s disease may occasionally develop into squamous cell carcinoma of the skin.
We have more information about Bowen’s disease.
People who have a weakened immune system (lowered immunity) have a higher risk of developing skin cancer. This includes people who:
- have had a kidney, liver, heart or lung transplant and take drugs that lower their immunity (immunosuppressants)
- have HIV or HPV
- have some types of blood cancer, such as chronic lymphocytic leukaemia (CLL).
People with lowered immunity are more likely to develop SCC. They are also more likely to develop BCC and melanoma compared with the general population.
If you take drugs that suppress your immune system, the benefit of taking them usually outweighs the risk of developing skin cancer. But it is important that you see your GP regularly to check for early signs of skin cancer.
Another possible, rare cause of non-melanoma skin cancer is over-exposure to certain chemicals, usually at a workplace. If you might be at risk from chemicals at your workplace, you should wear protective clothing and use protective equipment. Always follow the manufacturer’s instructions when using chemicals at home.
A genetic condition is when someone inherits a faulty gene from their parents. If you inherit a faulty gene, it increases your risk of developing certain health problems. Although most skin cancers are not caused by genetic conditions, some rare conditions carry a higher risk of developing skin cancer. These include:
- Gorlin syndrome
- xeroderma pigmentosum (XP).
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
National Institute for Health and Care Excellence (NICE) NICE pathways: Skin Cancer Treatment overview. (updated 2020)
Institute for Health and Care Excellence (NICE). Sunlight exposure: risks and benefits. NICE guideline [NG34] Published:2016.
British Journal of Dermatology. British Association of Dermatologists guidelines for the management of people with cutaneous squamous cell carcinoma. 2020.
National Institute for Health and Care Excellence (NICE) Cemiplimab for treating metastatic or locally advanced cutaneous squamous cell carcinoma [TA592] Published: 07 August 2019.
BMJ Best Practice. Overview of Skin Cancer. (updated 2019)
British Association of Dermatologists. Service Guidance and Standards for Mohs Micrographic Surgery (MMS). 2020.
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, Dr Samra Turajlic, Consultant Medical Oncologist.
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