Causes of skin cancer

• Too much sun exposure causes skin cancer
• Sun exposure in childhood affects your skin cancer risk as an adult
• Some people have higher risks of melanoma and need to take extra care
• Tanning is not a sign of health and offers little protection against burning
• Sunbeds are not safe and can also increase your risk 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.

Scientists estimate that heavy sun exposure causes at least two thirds (and probably more) of all malignant melanomas and up to 90% of all non-melanoma skin cancers (NMSCs) 3, 4.

People who receive the highest exposures to the sun have about 20-35% higher risks of melanoma 5, 6, 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 5, 6.

Recent studies have shown that intense, intermittent sun exposures, such as holiday sunbathing, pose the greatest risk of malignant melanomas 5, 6. The recent increase in the numbers of people holidaying abroad may contribute to the rising numbers of melanoma cases 5, 7, 8.

Experts agree that a person’s lifetime skin cancer risk is strongly affected by sun exposure during the first 15 years of life 9, 10. Studies indicate that sunburn during childhood can double a person’s risk of skin cancer 5, 6. 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 11, 12.

Some studies have found that sun protective behaviours during childhood can lead to fewer moles, a known risk factor for melanoma 13-16. For example, one study showed that regular sunscreen use during the first 18 years of life can reduce the risk of NMSC by 78% 17, 18.

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 19-23.

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 24
• have red or blond hair 24
• have blue, green or hazel eyes 24
• have freckles 24
• tan poorly and burn easily 20, 21
• have large numbers of moles 25, 26
• have a family history of skin cancer; up to one in ten melanomas occur in people with inherited predispositions 24, 27

Ethnic minorities with darker skins are up to 20 times less likely to develop melanoma than white Caucasians 28, 29. They have higher levels of the pigment melanin, which provides some protection from UV-induced damage 22. 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 30.

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 31, 32. 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 33, 34.

Studies have linked sunbed use to both malignant melanoma and NMSCs 1, 35. The International Agency for Research into Cancer (IARC) looked at 19 studies on sunbeds and cancer. They concluded that young people (under the age of 35) who use sunbeds have a 75% higher risk of melanoma. 36 Another study estimated that sunbeds cause 100 deaths from melanomas every year in the UK 37. Sunbeds also cause eye damage and premature skin ageing 38.

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. 36

Sunbeds are marketed as a ‘controlled’ way of getting a ‘safer’ tan 39. But actually, sunbeds are no safer than exposure to the sun itself 40. 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 41.

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 42. Studies have shown that up to half of all sunbed users suffer from sunburns 43. And in people who are prone to burning, UV-A from sunbeds can burn the skin faster than the sun 44.

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