About Cancer
Melanoma skin cancer is when abnormal cells in the skin start to grow and divide in an uncontrolled way. It starts in skin cells called melanocytes.
Read more about how cancer starts
There are 2 main categories of skin cancer:
non melanoma skin cancer - including , skin cancer and other rare types
melanoma skin cancer
This page is about melanoma skin cancer.
Read more about non melanoma skin cancer
Melanoma can also start in the layer of tissue lining some parts of your body. This is called mucosal melanoma. Melanoma can also start in the eye.
Read about other types of melanoma
The skin is a body organ. It does several jobs, including:
protecting the inside of the body from damage
helping to control body temperature
getting rid of some waste products through sweat
making vitamin D (this helps form and maintain our bones)
The skin is made up of 2 main layers, the epidermis and the dermis.
The thickness of the epidermis and the dermis varies depending on the part of the body the skin is covering. For example, the skin on the soles of your feet is quite thick, with an epidermis and dermis of about 5mm. The skin on your eyelids is much thinner, about 0.5mm.
Melanoma skin cancer can start anywhere on the skin. It may start:
in a mole
on a patch of normal skin
on the palms of the hands or soles of the feet
under the nails
Melanoma starts in cells in the skin called melanocytes. These cells are in the deep layer of the epidermis between the layer of basal cells.
Melanocytes make a pigment called melanin. This gives skin its colour. The pigment helps to protect the body from ultraviolet light (UV radiation) from the sun.
UV radiation can cause sunburn. This is a sign of damage to the genetic material () in skin cells. Over time, enough DNA damage can cause cells to grow out of control and lead to cancer.
In people with white skin, melanoma is more common on skin that has been exposed to the sun. But it can start anywhere.
It’s melanin that gives you a sun tan. Melanocytes make more melanin when they are exposed to the sun. This is then transferred to other skin cells to protect them against the sun's rays.
People with brown or black skin do not have more melanocyte cells than people with white skin. But their melanocytes are more active and make more of the pigment.
Rarely melanoma can develop in areas not exposed to the sun. Melanomas in the palms of the hands, soles of the feet and under the nails are normally a type of melanoma called acral melanomas. They are not related to exposure to the sun. Acral melanomas are more commonly diagnosed in people with brown or black skin.
Melanoma skin cancer can happen at any age, but it's more common in older people. Unlike most other cancer types, it's also quite common in younger people.
Ultraviolet radiation from the sun or sunbeds is the main environmental factor that increases the risk of getting melanoma skin cancer.
Other risk factors include:
skin type
hair and eye colour
number of moles
family history of melanoma
Read more about the risk factors for melanoma skin cancer
Around 19,400 people are diagnosed with melanoma skin cancer in the UK each year. The number of people diagnosed has increased over the last few decades.
Melanoma skin cancer is the 5th most common cancer in the UK.
Symptoms include changes to a mole, freckle or normal patch of skin. Doctors use a checklist of signs to look out for. But it helps to know what your skin normally looks like.
These pictures are only a guide to what melanoma skin cancers may look like. If you’re worried about a skin change it is important to get it checked by your GP.
The risk of developing melanoma skin cancer depends on many things including how much ultraviolet radiation you get from the sun and your skin type.
If you have symptoms of melanoma skin cancer you should see your GP. They might ask you to have some tests and may refer you to a specialist.
You might have a number of tests. This includes having a sample of tissue (biopsy) taken. Some people may have scans and tests on their lymph nodes.
The stage of a melanoma skin cancer tells you how deeply it has grown down into the skin. It also tells you if it has spread elsewhere in your body and how far.
Advanced melanoma skin cancer means the cancer has spread to another part of the body such as the liver, lungs or bone. Or it has come back after treatment.
Treatments include surgery, cancer drugs and sometimes radiotherapy. Which ones you have depends on the melanoma stage, where on your body it is and your general health.
Researchers are looking at the causes of melanoma skin cancer and new ways of treating it.
Last reviewed: 07 Feb 2025
Next review due: 07 Feb 2028
This section has been written, reviewed and updated by Cancer Research UK’s Patient Information Web Team. Thanks to the expert medical professionals and people affected by cancer who have helped to review this information.
Dr Victoria Akhras, Consultant Dermatologist
Dr Ricky Frazer, Consultant Oncologist
Mr Myles Smith, Consultant Surgical Oncologist and General Surgeon
our lay reviewers
About Cancer generously supported by Dangoor Education since 2010. Learn more about Dangoor Education
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