Causes of skin cancer

International health organisations agree that sun exposure is the main cause of skin cancers 1. Ultraviolet (UV) radiation from the sun damages DNA, which leads to the development of cancer 2.

Research has found that over eight in ten malignant melanomas are linked to excessive exposure to sunlight and use of sunbeds 3.

People who receive the highest exposures to the sun have about 20-35% higher risks of melanoma 4, 5. but sunburn increases the risk of this disease even more. Two analyses of several studies showed that sunburn at any age nearly doubles the risk of malignant melanomas.

Recent studies have shown that intense, intermittent sun exposures, such as holiday sunbathing, pose the greatest risk of malignant melanomas 4, 5. The recent increase in the numbers of people holidaying abroad may contribute to the rising numbers of melanoma cases 4, 6, 7.

Experts agree that a person’s lifetime skin cancer risk is strongly affected by sun exposure during the first 15 years of life 8, 9. Studies indicate that sunburn during childhood can double a person’s risk of skin cancer 4, 5. And migration studies have found that people who move to areas with higher UV exposures (like Australia) have higher melanoma risks if they arrive as children than as adults 10, 11.

Some studies have found that sun protective behaviours during childhood can lead to fewer moles, a known risk factor for melanoma 12-15. For example, one study showed that regular sunscreen use during the first 18 years of life can reduce the risk of NMSC by 78% 16, 17

It is especially important to teach children sensible sun behaviours in the first few years of life when they are more likely to develop unhealthy attitudes to sun exposure 18-22.

Studies have shown that some people have a higher risk of melanoma than others. You should take extra care in the sun if you:

• have fair skin 23
• have red or blond hair 23
• have blue, green or hazel eyes 23
• have freckles 23
• tan poorly and burn easily 19, 20
• have large numbers of moles 24, 25
• have a family history of skin cancer; up to one in ten melanomas occur in people with inherited predispositions 23, 26

Ethnic minorities with darker skins are up to 20 times less likely to develop melanoma than white Caucasians 27, 28. They have higher levels of the pigment melanin, which provides some protection from UV-induced damage 21. But people with darker skin can still burn and develop skin cancers, especially on non-pigmented parts of the body like the soles of the feet, or the nail bed 29.

Far from being a sign of health, science tells us that a tan is a reaction to DNA damage in the skin. It is a sign that your body is trying to repair damage that has already happened 30, 31. And pre-holiday tans or sunbed tans offer very little protection against the sun. Some studies have found that tans only offer protection equivalent to using factor 3 sunscreen 32, 33.

Studies have linked sunbed use to both malignant melanoma and NMSCs 1, 34. A comprehensive review published in 2012 of studies on sunbeds and cancer concluded that people who use sunbeds for the first time before the age of 35 have a 59% higher risk of melanoma than never users. 35 Another study estimated that sunbeds cause 100 deaths from melanomas every year in the UK 36. Sunbeds also cause eye damage and premature skin ageing 37.

IARC also concluded that sunbeds provide no positive health benefits. They do not protect against further damage from the sun and they do not help your skin to make enough vitamin D. 35

Sunbeds are marketed as a ‘controlled’ way of getting a ‘safer’ tan 38. But actually, sunbeds are no safer than exposure to the sun itself 39. It is a common misconception that sunbeds emit only UV-A radiation, and not UV-B, the type which causes most sunburns. But all sunbeds emit some measure of UVB, and even this tiny proportion is enough to cause substantial damage to our skin 40.

UVA can also damage the skin and the levels of UV-A from sunbeds can be over 10 times higher than that of the midday sun 39. Studies have shown that up to half of all sunbed users suffer from sunburns 41. And in people who are prone to burning, UV-A from sunbeds can burn the skin faster than the sun 42.

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