Melanoma skin cancer

Melanoma is a type of skin cancer that has a high risk of spreading.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2023

What is melanoma skin cancer?

Melanoma is when certain cells in your skin (melanocytes) start to grow abnormally and in an uncontrolled way – often as a new mole or a change in an existing mole. There are around 9,000 new cases of melanoma in the UK each year. Although it’s an uncommon form of skin cancer, melanoma is the second most common cancer in people aged 25 to 49. It’s more common in older people.

Sudden, intense sun exposure (for example getting sunburnt on holiday) is thought to be the biggest risk factor for melanoma.

If melanoma isn’t treated early, it can grow deeper into the skin and eventually cancer cells can enter the blood or lymph system. This means the melanoma has become metastatic and spread to other organs such as the lung, liver or brain, making it much harder to treat.

How to tell if you have melanoma skin cancer

A melanoma often grows as a new mole on fresh skin, although a change in an existing mole can also be a sign of melanoma. This can be anywhere on the body but less common on areas usually protected from sun exposure.

When assessing a mole, it’s useful to remember the ABCDE rule to identify a melanoma:

  • Asymmetry of the mole – it’s not a circle or oval
  • Border irregularity – the mole doesn’t have a smooth edge
  • Colour being uneven – the mole isn’t all one colour
  • Diameter more than 6mm
  • Evolving – the mole is changing or getting bigger

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

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Diagnosis and tests for melanoma skin cancer

Your GP will examine your mole, and may use a dermatoscope (a handheld microscope) to investigate the mole more closely or refer you to a specialist if the mole looks suspicious.

If the mole is suspicious, your doctor will probably advise to have it cut out by a specialist. The tissue removed is then analysed to confirm the diagnosis and decide if further treatment or assessment is required, such as sentinel lymph node biopsy – a procedure to test if the cancer has spread.

Melanoma stages

Melanoma is staged from one to four. Stage one is early stage, where the melanoma is only in the skin and there's no sign that it’s spread. There’s a good chance of curing the condition by simply cutting it out. Stages two to four is when the disease has spread to other parts of your body, depending on how far or how much.

Causes of melanoma skin cancer

You’re more at risk of melanoma if you have:

  • Fair skin
  • Skin that burns easily in the sun
  • Many moles or freckles
  • A family history of melanoma
  • A weakened immune system – for example due to an infection or are taking immunosuppressive medication

Common treatments for melanoma skin cancer

A team of specialists will help you decide on your treatment, considering:

  • The type of cancer you have
  • The stage of your cancer
  • Your overall health


Removing the mole (excisional biopsy) can cure the melanoma if it’s caught early. If not, then a wide local excision is usually needed – where your doctor removes more normal-looking skin from around the mole to reduce the chance of the melanoma coming back.

If the melanoma has spread to nearby lymph nodes, further surgery (lymph node dissection) may be needed to remove the affected nodes.

Other treatments

Even if it’s not possible to cure the cancer, a multi-disciplinary team can recommend further treatment to help control the growth and ease your symptoms. This can include:

  • Chemotherapy – can’t cure melanoma, but can help control it and improve symptoms
  • Biological treatments – new types of drugs that may be given as part of a clinical trial
  • Medicines to help alleviate the symptoms
  • Radiotherapy – to shrink tumours and control symptoms or sometimes offered after surgery to lower the chance of it coming back