Bonn  - Skin cancer is one of the most common forms of the disease and in Germany alone 2,700 people die of it. However, if recognized early enough and treated, it can often be cured.

Ultra violet (UV) rays remain the main risk factor, whether they come from a tanning salon or the sun. But the danger also is influenced by a person's skin type.

"Types one and two have blonde or red hair, fair skin with freckles and burn very easily. These people are especially susceptible to skin cancer," says Eva Kalbheim of Bonn-based German Cancer Aid.

But people with darker complexions and hair can also get skin cancer. "Alongside the genetic risks, the development of cancer is influenced by personal behaviour," says Kalbheim. People who sunbathe frequently and suffer many burns have enormously higher risks.

A study of about 100,000 Scandinavian women showed that high UV ray exposure in their youth could lead to many problems later, says biophysicist Ruediger Greinert of the Dermatological Centre in Buxtehude.

"Using a tanning salon before your 35th birthday increases the risk of a melanoma by 75 per cent later in life, according to the study."

Physicians recommend regular skin check-ups. "A person should check all over every two months to see if there have been any changes. If anything itches or bleeds for no apparent reason, you should go to a doctor," advises Eckhard Breitbart of the Hamburg- based ADP Working Group on Dermatological Prevention.

Dark birthmarks require special attention because melanomas can manifest themselves inside the dark pigmentation. This is the most dangerous form of cancer as it frequently metastasizes.

"When you check your birthmarks, you should use the so-called ABCD rule," says Breitbart.

The A stands for asymmetry. An at-risk birthmark will not have a regular shape, like the circles and ovals found in so many other skin blemishes.

The B - for borders - is also important. "If the border isn't regular or bleeds outside the original shape, then there is reason for concern," says Breitbart. A healthy birthmark will have sharp and even borders.

The C is for colour. A harmless birthmark will tend to be a uniform light brown. Multi-coloured birthmarks are a sign of potential danger.

Finally, there is the D for diameter. "People used to use the pencil test," says Breitbart. "If the birthmark was smaller than an unsharpened end of a pencil, then it was presumed to be safe."

However, that is no longer the case. Breitbart advises keeping a close eye on any birthmark with a diameter of two millimetres or more.

If there is reason to think that a birthmark has experienced some changes, it is imperative to have a doctor perform an examination. Skin cancer is very manageable in its early stages and cannot metastasize. An operation at this stage will usually leave nothing more behind than a small scar. (dpa)