Melanoma is a type of cancer that usually develops in the skin. It starts in cells called melanocytes, which produce the pigment melanin, that give your skin its colour. Melanocytes are also found in your eyes, under your nails, and inside your mouth, nose and organs such as the intestines. Because of this, melanoma can also develop in these areas of your body, although this is rare.
Melanoma usually develops in areas of previous sunburn or with lots of sun exposure, such as your back, arms, legs and face, but it can appear on the skin of any part of your body. Often, melanoma starts as a new spot on your skin, but it may also develop at the site of an existing mole.[1,2]
What are the risk factors for melanoma?
Why some people get melanoma is not completely clear and anyone can get the disease. However, some factors are known to increase the chance of a person developing this disease, called ‘risk factors’. Having a risk factor does not mean that you will definitely get the disease.
About 9 in 10 cases of melanoma are caused by sun exposure, and just one sunburn that blisters can double the chance of a person getting melanoma later in life. However, melanoma is not just caused by one-off sunburns, but also the daily exposure of your skin to the sun. Some other risk factors for melanoma are:[1,4]
Previous skin cancers, as these are ‘markers’ of increased sun exposure
Close blood relatives (parents, siblings and children) with melanoma
A skin type that burns easily, usually called ‘fair skinned’
Red, blond or fair hair and light-coloured eyes
Skin damage due to sunburn
Many moles (more than 50–100) and large, irregular or ‘funny-looking’ moles
A weakened immune system, such as in people who have undergone organ transplants
Genetic risk factors – alterations in certain genes play a role in the cause of many melanomas.
What does melanoma look like?
The first sign of melanoma is often a change in an existing mole or the development of a new pigmented (coloured) spot or unusual looking growth on your skin.
To help you identify potential melanomas, it can be useful to remember the letters ABCDE, which stand for:[1-3,5-7]
Asymmetrical shape – moles with irregular shapes, where one half is different from the other
Border is irregular – the spot has uneven rather than smooth edges
Colour changes – spots with different or uneven colours, different from your other moles
Diameter – larger moles, especially those bigger than the end of a pencil (about 6mm)
Evolving – changes in an existing mole, such as changes in size, shape or colour, or changes such as new itchiness or bleeding.
How is melanoma diagnosed?
When diagnosing melanoma, your doctor will examine the spot or mole that you are concerned about and will do a general check of your skin. Your doctor will probably use a special magnifying glass called a dermoscope. They may also feel your lymph nodes in the area near the spot or mole that is being checked, as this is one of the first places the cancer can spread to. Lymph nodes are small structures, shaped a bit like beans, which form part of your body’s immune system. While melanoma can sometimes be detected by just looking at the skin, the only accurate way to make a diagnosis of melanoma is with a biopsy.
Punch biopsy – your doctor uses a tool with a circular blade that is pressed into the skin around a suspicious mole to remove a round piece of skin
Excisional biopsy – the entire mole or growth is removed along with a small border of normal-appearing skin Incisional biopsy – the most irregular part of a mole or growth is taken for laboratory analysis
What are the stages of melanoma?
If you are diagnosed with melanoma, your doctor may refer to its ‘stage’. The stages of melanoma are described on a scale from 0 to IV and refer to the different phases of the disease. Melanoma stage 0 to I is called ‘early’, stage II is called ‘intermediate or high-risk’ and stage III to IV is called ‘advanced’:
Stage 0 – cancer cells are beginning to form a tumour, but are contained in the mole or spot and have not spread deeper into the skin or to any other part of your body.
Stage I – cancer cells have formed a tumour that has spread beyond the epidermis (first layer of your skin) into the dermis (second, deeper layer of your skin), but are still small and do not show signs that indicate a high risk of spreading further.
Intermediate or ‘high-risk’ melanoma
Stage II – the tumour is still ‘localised’ meaning still contained within the skin, but they are larger than stage I tumours and have a higher risk of spreading to nearby lymph nodes and to other parts of the body.
Stage III – melanoma cancer cells from the tumour have begun to spread and may have reached the lymph nodes. Your doctor may perform further tests, which could involve removing the lymph nodes to help understand how far the melanoma cancer cells have spread.
Stage IV or metastatic – the melanomas cancer cells have spread to other parts of the body such as the brain, liver, kidney and lungs and formed further tumours. Your doctor may perform scans of your chest, head, abdomen and pelvis to identify where the melanoma cancer cells have spread to.
What are the treatment options for melanoma?
Treating early melanoma
Early-stage melanoma is generally treated with surgery to remove the melanoma cancer cells, often with no further treatment necessary. For a small tumour that is Stage 0 or I, the entire tumour can be removed during the biopsy and further surgery may not be needed.[1,3]
Treating advanced melanoma
For advanced melanoma, when cancer cells have reached the lymph nodes or spread to other parts of the body, additional treatment may be needed. [1,3]
Treatment options for advanced melanoma include:
Chemotherapy – A type of treatment that uses anti-cancer drugs (known as cytotoxic drugs) to stop cancer cells from growing and destroy them 
Radiation therapy – Involves high-powered beams of energy, such as x-rays, to kill cancer cells
Biological therapies/immunotherapies – These drugs use the body’s own immune system to target and destroy the cancer cells. Biological therapies used to treat melanoma include interferon and interleukin-2, ipilimumab, nivolumab, and pembrolizumab. They may be used alongside chemotherapy.
Targeted therapy – Some patients with melanoma have a specific change in their genetic material (called a mutation). One of the most common mutations in melanoma is called BRAF, and your doctor may perform tests to see if your melanoma has this mutation. Patients who have the BRAF mutation may be treated with a type of drug called a targeted therapy. Examples of targeted therapies that work in patients with the BRAF mutation include vemurafenib, dabrafenib, cobimetinib and trametinib.
New drugs or new combinations of drugs – Your doctor may also suggest that you take part in a clinical trial. Clinical trials investigate new drugs or new combinations of drugs and compare them with the current therapies already available. If you would like to know more about clinical trials, speak to your doctor.
What is the outlook for a person with melanoma?
The outlook for melanoma depends on several factors, including tumour size and location, how fast the tumour cells are growing and what stage it is at when you start treatment (0 to IV).[3,9] Please talk to your doctor about the outlook of your melanoma.
Find related clinical trials
Use our search to find clinical trials on Genentech Clinical Trials associated with Skin Cancer