What increases your risk of melanoma?

There are four basic facts that all experts agree on:

• Spending time in the sun is a normal part of life. Our bodies need UVB rays to make essential vitamin D.
• 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 be different for different people, depending 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 may 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 skin 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 never, or only rarely, exposed to the sun. But it is still possible for melanoma to develop there too – for instance on your scalp, in your genital area, or on the skin beneath your toenails or fingernails. So the role of the sun depends on many different factors – and UV radiation certainly isn't the only cause of melanoma.

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, and 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 melanoma. 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 by law 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 to prepare their skin for the sun in order to avoid sunburn. But the kind of tan you get by using tanning beds hardly protects you at all from sunburn. Although the UVA radiation in tanning beds makes you tan quickly, the tan doesn't last long.

People with fair skin generally have a higher risk of developing melanoma than people with naturally dark 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 regions. People with even darker or black skin (types V and VI) have their roots in places like certain areas of Asia or Africa.

Moles (medical term: nevi) are benign skin growths that are light or dark in color. They may be present at birth or develop later on in life. Lentigines (melanocytic nevi) develop from pigment-producing cells known as melanocytes and are brown in color. But moles and lentigines are often simply called "moles" by many people.

People who have a lot of moles or lentigines are more likely to develop melanoma. The more you have, the higher the risk. Abnormal or large moles are also associated with a greater risk of skin cancer.

People who have already had melanoma in the past are more likely to develop melanoma in the future. If melanoma returns, it usually does so within five years after the first tumor has been removed. Your risk of melanoma is also higher if other members of your family have had it before.

Some genetic diseases such as xeroderma pigmentosum increase the risk of melanoma. The risk is also greater in people who have a weak immune system. This includes people who take medication to suppress their immune system following an organ transplant.

Flight attendants and pilots also have a slightly higher risk of melanoma, but it's not clear why.