What increases your risk of non-melanoma skin cancer?

The amount of UVB rays you are exposed to every day will depend on where you live. The differences between different locations within Germany and similar countries are generally small, though. UVB exposure tends to be more of a problem in mountainous regions than in lower regions. Snow, water and light-colored sand reflect UV light, increasing the radiation levels.

There are much bigger differences between different places around the world. UV exposure is greater in places where the sun is high in the sky and in places where the ozone layer is thin. So the risk of skin cancer is particularly high in countries that are close to the equator and in countries near to the hole in the ozone layer above the Antarctic.

There are four basic facts that all experts can agree on:

• Spending time in the sun is a normal part of life. Our bodies need UVB rays to make essential vitamin D, too.
• Sunburn should be avoided whenever possible.
• Too much sun increases your risk of skin cancer.
• Children are at higher risk than adults.

But how much sun is “too much” sun? There is no simple answer to this question. This is partly because the answer will depend on individual factors like the type of skin you have. But it is also because the link between the sun and cancer is not yet fully understood.

The frequency, duration and intensity of exposure to UV radiation varies greatly, too: People who work outside may spend several hours a day in the sun during the summer months. An office worker would be more likely to spend time in the sun at weekends or on vacation. Some people are keen to get a tan, while others aren't.

We also spend time in the sun while doing other things – for example, on the way to work, while out running errands, or enjoying free time outdoors. Some people consider this to be less of a problem than sun exposure while consciously sunbathing.

What’s more, different parts of your body are exposed to very different amounts of UV light: Your face, neck, hands and arms are exposed to a lot more sunlight than the rest of your body. Some other parts of your body are only rarely exposed to the sun.

As you go through life, each area of your skin is exposed to different total amounts of UV radiation. Scientists still don't agree on how much of a role the total amount of UV light exposure plays, or whether it makes a difference if you have days or weeks with a lot of sun followed by days or weeks with only very little sun. This is the case when a child plays in the midday sun for hours while on summer vacation, for example, and mostly stays indoors the rest of the year.

The light used in tanning beds has UV rays in it. Because of this, people who use them regularly probably increase their risk of developing basal cell carcinoma or squamous cell carcinoma. This is particularly true for anyone under the age of 20 years. In Germany and other countries, children and teenagers under the age of 18 are forbidden to use tanning beds or sun lamps.

The amount of UVA and UVB exposure from a tanning bed depends on the light tubes used. This varies depending on the make and model of the tanning bed, as well as on how old the light tubes are. Newer models are not allowed to emit more UV light than the midday sun at the equator on cloudless days.

Some people use tanning beds in order to prepare their skin for the sun and avoid sunburn. But the kind of tan you get by using tanning beds hardly protects you from sunburn. The UVA rays in tanning beds tan your skin quickly, but the effect doesn't last very long.

Fair-skinned people generally have a higher risk of developing non-melanoma cancer than people who have naturally darker skin.

People who have fair skin (types I and II) have a pale complexion, often with freckles, and never get a tan (type I) or only tan a little (type II). They are very prone to sunburn. People who are sensitive to sunlight usually have light-colored eyes and hair, such as blue or green eyes and red or blond hair.

People with darker skin are less sensitive to UV rays.

The following can help you determine what type of skin you have:

Very light skin and light skin (types I and II) are typical in places like Scandinavia and Great Britain, and people who have a medium brown skin tone with dark eyes and dark hair (type IV) mainly live in the Mediterranean and geographically similar areas. People with even darker or black skin (types V and VI) have their roots in places like certain areas of Asia or Africa.

UV light can also cause abnormal cell changes that are likely to lead to cancer, known as actinic keratosis. Actinic keratosis often looks like a brownish or reddish scaly patch of skin. It may develop into squamous cell carcinoma.

People who smoke might have a higher risk of developing squamous cell carcinoma. Certain toxins such as arsenic and certain chemicals can also increase the risk of non-melanoma skin cancer.

Non-melanoma skin cancer is more common in people who have a job that involves working outside a lot.

The risk is also greater in people who have a weak immune system. That mostly includes people who take medication to suppress their immune system, for instance following an organ transplant. Some skin conditions such as psoriasis can be treated using UV light. One side effect of this kind of treatment is an increased risk of squamous cell carcinoma.

A number of hereditary diseases increase the risk of non-melanoma skin cancer too. These include xeroderma pigmentosum (XP) and nevoid basal-cell carcinoma syndrome (NBCCS).

If you have already had skin cancer in the past you are more likely to get skin cancer in the future. The risk will depend on

• what type of skin cancer you had the first time,
• whether it was discovered at an early or late stage,
• how it was treated,
• where on your body it was,
• whether other people in your family have or had skin cancer,
• what type of skin you have, and
• how strong the UV rays are where you live.

People who have had basal cell carcinoma once are quite likely to get it again: Out of 100 people who have already had basal cell carcinoma,

• about 29 will develop it again,
• around 4 will develop squamous cell carcinoma, and
• fewer than 1 out of 100 will have melanoma.

About 13 out of 100 people who have had squamous cell carcinoma will get it again, 16 of them will develop basal cell carcinoma, and fewer than 1 will develop melanoma.