How does the sun and UV cause cancer?

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  • Too much ultraviolet (UV) radiation from the sun can damage DNA in your skin cells and cause skin cancer.
  • In the UK almost 9 in 10 cases of melanoma, the most serious type of skin cancer, could be prevented through enjoying the sun safely and avoiding sunbeds.
  • Getting sunburnt just once every 2 years can triple your risk of melanoma skin cancer.

What is UV?

The sun naturally gives out ultraviolet radiation (UV), whilst the UV from sunbeds is artificial. There are 2 main types of UV rays that damage our skin. Both types can cause skin cancer:

  • UVB is responsible for the majority of sunburns.
  • UVA penetrates deep into the skin. It ages the skin but contributes much less towards sunburn.

A third type of UV ray, UVC, could be the most dangerous of all, but it is blocked out by the ozone layer and doesn’t reach the earth's surface.

You can’t feel UV rays – the heat from the sun comes from infrared rays, which can’t burn you. This is why people can still burn on cool days.

How can UV cause skin cancer?

Too much UV radiation from the sun or sunbeds can damage the genetic material (the DNA) in your skin cells. If enough DNA damage builds up over time, it can cause cells to start growing out of control, which can lead to skin cancer. Anyone can develop skin cancer, but some people can have a higher risk.

Find out about your risk of sunburn here

It’s important to remember that skin damage doesn’t just happen on holiday or in hot, sunny places. The sun is often strong enough to cause damage in the UK, even when it’s cloudy.

What is sunburn?

Sunburn is skin damage and your body’s response to try to repair it – it’s a short-term warning for potential long-term DNA damage, and is a clear sign that the DNA in your skin cells has been damaged by too much UV radiation. Getting sunburn, just once every 2 years, can triple your risk of melanoma skin cancer.


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Sunburn doesn’t have to be raw, peeling or blistering. If your skin has gone pink or red in the sun, it’s sunburnt. For people with darker skin, it may just feel irritated, tender or itchy.

Find out the best ways to enjoy the sun safely

What should I do if I get sunburnt?

If you notice your skin becoming pink or red, you should come out of the sun and cover up to help stop any more damage from happening. Putting on more sunscreen won’t help and won’t let you safely stay out in the sun for longer.

After sun lotion can help sunburnt skin feel better, but it can’t repair any DNA damage. 

Getting sunburnt once doesn’t mean you will definitely develop skin cancer. But the more you get sunburnt the higher your risk of melanoma skin cancer. Reduce your risk of sunburn and protect your skin in the future by using a combination of shade, clothing and sunscreen.

Can skin cancer be invasive?

Yes. Melanoma can sometimes grow down through the layers of skin. If a tumour grows through the wall of a blood or lymph vessel, cancer cells can break off and spread to other parts of the body. This is why skin cancer is usually easier to treat successfully when it is caught at an early stage. It is much rarer for non-melanoma skin cancers to be invasive.

What is melanoma?

International Agency for Research on Cancer. Radiation. Vol 100 (2012)

Brown, K. F. et al. The fraction of cancer attributable to known risk factors in England, Wales, Scotland, Northern Ireland, and the UK overall in 2015. Br. J. Cancer. 118, 1130-1141 (2018)

Dennis, L. K. et al. Sunburns and risk of cutaneous melanoma, does age matter: a comprehensive meta-analysis. Ann Epidemiol. 18, 614-627 (2008). doi:10.1016/j.annepidem.2008.04.006.Sunburns.

Amano S. Characterization and mechanisms of photoageing-related changes in skin. Damages of basement membrane and dermal structures. Exp Dermatol. 25, 14-19 (2016). doi:10.1111/exd.13085

Eilers S, Bach DQ, Gaber R, et al. Accuracy of self-report in assessing Fitzpatrick skin phototypes I through VI. JAMA dermatology. 149(11), 1289-1294 (2013). doi:10.1001/jamadermatol.2013.6101.

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