Melanoma is a type of skin cancer that can spread to other organs in the body.

The most common sign of melanoma is the appearance of a new mole or a change in an existing mole. This can happen anywhere on the body, but the back, legs, arms and face are most commonly affected.

In most cases, melanomas have an irregular shape and more than one colour. They may also be larger than normal moles and can sometimes be itchy or bleed.

An "ABCDE checklist" has been developed for people to tell the difference between a normal mole and a melanoma. Watch a visual guide to moles.

Read more about the symptoms of melanoma.

Why does melanoma happen?

Melanoma happens when some cells in the skin begin to develop abnormally. It is thought that exposure to ultraviolet (UV) light from natural or artificial sources may be partly responsible.

Certain things can increase your chances of developing melanoma, such as having:

• lots of moles or freckles
• pale skin that burns easily
• red or blonde hair
• a family member who has had melanoma

Read more about the causes of melanoma.

Diagnosing melanoma

See your GP if you notice any change to your moles. Your GP will refer you to a specialist clinic or hospital if they think you have melanoma.

In most cases, a suspicious mole will be surgically removed and studied to see if it is cancerous. This is known as a biopsy.

You may also have a test to check if melanoma has spread elsewhere in your body. This is known as a sentinel node biopsy.

Read more about diagnosing melanoma.

How is melanoma treated?

The main treatment for melanoma is surgery, although your treatment will depend on your circumstances.

If melanoma is diagnosed and treated at an early stage, surgery is usually successful.

If melanoma isn't diagnosed until an advanced stage, treatment is mainly used to slow the spread of the cancer and reduce symptoms. This usually involves medicines, such as chemotherapy.

Read more about treating melanoma.

Once you have had melanoma, there is a chance it may return. This risk is increased if your cancer was widespread and severe.

If your cancer team feels there is a significant risk of your melanoma returning, you will probably need regular check-ups to monitor your health. You will also be taught how to examine your skin and lymph nodes to help detect melanoma if it returns.

Who is affected

Melanoma is the 5th most common cancer in the UK with around 13,000 new cases of melanoma diagnosed each year.

More than a quarter of cases are diagnosed in people under 50, which is unusual compared to most other types of cancer. It's also becoming more common in the UK over time, thought to be caused by increased exposure to UV light from the sun and sunbeds.

More than 2,000 people die every year in the UK from melanoma.

Can melanoma be prevented?

Melanoma is not always preventable, but you can reduce your chances of developing it by limiting your exposure to UV light.

You can help protect yourself from sun damage by using sunscreen and dressing sensibly in the sun. Sunbeds and sunlamps should also be avoided.

Regularly checking your moles and freckles can help lead to an early diagnosis and increase your chances of successful treatment.

Read more about preventing melanoma.