Cancer, skin (melanoma)

Melanoma, also called malignant melanoma, is a rare type of skin cancer. Melanoma is serious because the cancer can spread to other organs in the body. When cancer spreads it is known as metastasis. Melanoma can start in an existing mole but it can also develop in normal-looking skin.

How common is melanoma?

Melanoma is relatively rare and makes up 10% of all skin cancer cases. However, melanoma is also responsible for most deaths due to skin cancer. Approximately 100 people die every year in Ireland due to melanoma.

The main cause of melanoma is believed to be over-exposure to the sun. Overusing sunbeds and sunlamps may also increase your risk of developing melanoma.


The outlook for melanoma depends on how far the cancer has progressed when treatment begins. If melanoma is diagnosed and treated in its early stages, the outlook is good and there is a high chance of it being cured.

If diagnosis and treatment do not begin until the melanoma has reached an advanced stage, the outlook is poor and the chances of being completely cured are low.

Malignant is a term used to describe a life-threatening or worsening condition. In the case of tumours, malignant means cancerous.
Metastasis is when cancer or disease spreads to other parts of the body.

Melanomas can appear anywhere on your body, but the back, legs, arms and face are the most common locations.

The first sign of a melanoma is often the appearance of a new mole or a change in the appearance of an existing mole. Normal moles are usually a single colour, round or oval in shape and are not larger than 6mm (1/4 inch) in diameter. Melanomas are more likely to have an irregular shape and be more than one colour, and they are often larger than 6mm (1/4 inch) in diameter. A melanoma may also be itchy and may bleed.

A good way to tell the difference between a normal mole and a melanoma is to use the ABCD checklist:

  • A stands for asymmetrical - melanomas have two very different halves and are an irregular shape.
  • B stands for (irregular) border - unlike a normal mole, melanomas have a notched or ragged border.
  • C stands for (two or more) colours - melanomas will be a mix of two or more colours.
  • D stands for (large) diameter - unlike most moles, melanomas are larger than 6mm (1/4 inch) in diameter.

If you are concerned about one of your moles, see your GP as soon as possible.


The body is made up of millions of different types of cells. Cancer happens when some of the cells multiply in an abnormal way. When cancer affects organs and solid tissues, it causes a growth called a tumour to form. Cancer can occur in any part of the body where the cells multiply abnormally.

How does cancer spread?

Left untreated, cancer can quickly grow and spread, either in the skin or the blood, or to other parts of the body. This usually happens through the lymphatic system.

The lymphatic system is a series of glands that are spread throughout your body and linked together in a similar way to the blood circulation system. If you have a cold or flu, the glands that come up in the neck are the lymph glands (also called lymph nodes). The lymph glands produce many of the cells that are needed by your immune system.

If the cancer reaches your lymphatic system, it can spread to any other part of your body, including your bones, blood and organs.


The leading cause of melanomas is exposure to sunlight. Sunlight contains ultraviolet (UV) light that can affect the skin. There are two main types of UV - ultraviolet A (UVA) and ultraviolet B (UVB). Both UVA and UVB damage skin over time, making it more likely for skin cancers (including melanomas) to develop. Artificial sources of light, such as sunlamps and tanning beds, may also increase your risk of developing melanoma skin cancer.

Risk factors

Factors that increase your risk of developing melanoma include:

  • having pale skin that tends to burn and not tan easily
  • if a family member has had melanoma
  • having red or blonde hair
  • having blue eyes
  • having a large number of moles
  • having a large number of freckles
  • having a condition that suppresses your immune system, such as HIV
  • taking medicines that suppress your immune system (immunosuppressants)
  • having certain rare skin diseases that make you more likely to get skin cancer

All the above risk factors make your skin more sensitive to the effects of the sun.


Your GP will examine your skin and decide if you need to be referred for further assessment. Some GPs take digital photographs of any suspected tumours so they can email them to a specialist for assessment.


If your GP decides that a suspicious looking mole could be the result of melanoma, you will be referred to a dermatologist for further testing. A dermatologist is a doctor who specialises in skin conditions. The dermatologist may do a biopsy. This is a small operation where a suspect mole is removed from your skin so that it can be studied under a microscope. This shows whether the mole is cancerous.

If cancer is confirmed, you will usually need a further operation to remove a wider margin of skin. You may also be recommended to have a further operation to see if the melanoma has already spread (see below).

Further tests

If your cancer has a higher risk of spreading to the lymphatic system into other organs, bones or your blood stream, further testing may be carried out. There are certain features of melanoma that make it more likely to spread – how thick the tumour is, how active a tumour it is, or if it is ulcerated. If your tumour has these risky  features you may be offered a sentinel lymph node biopsy.    If your tumour does not have these features you may not need a sentinel node biopsy or any other tests.


Sentinel lymph node biopsy

If melanoma spreads, it will usually begin spreading in a predictable way through channels in the skin (called lymphatics) to the nearest group of glands (called lymph nodes).

These are the same glands that come up in your neck when you have a cold or a sore throat, but they are found everywhere in the body. They are part of the body's immune system, and they act as a sort of way-station for fluid in the skin as it circulates slowly around the body.

Microscopic amounts of melanoma can spread through the lymphatics to the lymph nodes. A melanoma on the arm will most often spread to lymph nodes in the armpit, while a melanoma on the leg will most often spread to glands at the groin.

Sentinel lymph node biopsy is a test to determine whether microscopic amounts of melanoma (less than would show up on any X-ray or scan) might already have spread to the lymph nodes.

The surgeon injects around your scar a combination of a blue dye and a weakly radioactive chemical. This will usually be done just before the wider margin of skin is removed. This dye and the radioactivity will follow the same channels in the skin as any melanoma, and the first lymph node that they get to would, logically, be the first lymph node that any cancer would reach - the "sentinel" lymph node.

Using first the radioactivity and then the blue dye, the surgeon can selectively remove the sentinel node (or sometimes nodes), leaving all the others intact. The node is then given to a pathologist who will be asked to examine it to identify or exclude a single microscopic speck of melanoma (this process can take several weeks).

If the sentinel lymph node is clear of melanoma, it is extremely unlikely (although not impossible) that any other lymph nodes are involved. This is reassuring, since patients whose melanoma has spread to the lymph nodes are much more likely to have their melanoma spread elsewhere.

If the sentinel lymph node contains melanoma, there is around a 20% risk that at least one other lymph node in the same group will contain melanoma. Under these circumstances, your surgeon will discuss with you the possibility of having a much bigger operation to remove all the remaining lymph nodes in the affected group.

This bigger operation is often called a completion lymph node dissection or completion lymphadenectomy.

Other tests you may have include:

Treatment overview

People with cancer should be cared for by a multidisciplinary team (MDT). This is a team of specialists who work together to provide the best treatment and care.

The team often consists of a dermatologist, a plastic surgeon, an oncologist (a radiotherapy and chemotherapy specialist), a pathologist and a specialist nurse. Other members may include a dietitian and occupational therapist, and you may have access to clinical psychology support.

Health professionals use a staging system to describe how far melanoma has grown into the skin (the thickness) and whether it has spread. The type of treatment you receive will depend on what stage the melanoma has reached.

The stages of melanoma can be described as:

  • Stage 0 - the melanoma is on the surface of the skin. 
  • Stage 1A - the melanoma is less than 1mm thick 
  • Stage 1B - the melanoma is 1-2mm thick or the melanoma is less than 1mm thick and the surface of the skin is broken (ulcerated).
  • Stage 2A - the melanoma is 2-4mm thick or the melanoma is 1-2mm thick and it is ulcerated.
  • Stage 2B - the melanoma is thicker than 4mm or the melanoma is 2-4mm thick and it is ulcerated.
  • Stage 2C - the melanoma is thicker than 4mm and it is ulcerated.
  • Stage 3A - the melanoma has spread into one to three nearby lymph nodes but they are not enlarged. The melanoma is not ulcerated and has not spread further.
  • Stage 3B - the melanoma is ulcerated and has spread into one to three nearby lymph nodes but they are not enlarged, or
    the melanoma is not ulcerated and it has spread into one to three nearby lymph nodes and they are enlarged, or the melanoma has spread to small areas of skin or lymphatic channels but not to nearby lymph nodes.
  • Stage 3C - the melanoma is ulcerated and has spread into one to three nearby lymph nodes and they are enlarged, or
    the melanoma has spread into four or more lymph nodes nearby.
  • Stage 4 - the melanoma cells have spread to other areas of the body, such as the lungs, brain or other parts of the skin.


Stage 1 melanoma

Treating stage 1 melanoma will involve surgically removing the melanoma as well as a small area of skin around it. This is known as surgical excision.

If a surgical excision is likely to leave a significant scar, it may be done in combination with a skin graft. A skin graft involves removing a patch of healthy skin, which will usually be taken from a part of your body where any scarring cannot be seen, such as your back. It is then connected, or grafted, to the affected area.

Once the melanoma has been removed, there is little possibility that it will return and no further treatment should be required. You will probably be asked to come for follow up appointments before being discharged. 

Stage 2 and 3 melanoma

As with stage 1 melanomas, any affected area of skin will be removed and a skin graft carried out if necessary.

If the melanoma has spread to nearby lymph nodes, you may need further surgery to remove them. This is known as a block dissection and is carried out under a general anaesthetic.

While the surgeon will try to ensure that the rest of your lymphatic system can function normally, there is a risk that the removal of lymph nodes will disrupt the lymphatic system, leading to a build-up of fluids in your limbs. This is known as lymphoedema.

Once the melanoma has been removed, you will need to have follow-up appointments to see how you are recovering and to watch for any sign of the melanoma returning.

You may be offered treatment to try to prevent the melanoma from returning. This is called adjuvant treatment. Currently, there is not much evidence that adjuvant treatment helps prevent melanoma from coming back. However, ongoing clinical trials are looking into this and you may be asked to join one. These trials investigate whether drug treatment could be used to reduce the risk of the melanoma returning.

You may also have a sentinel lymph node biopsy to see if the melanoma has spread to nearby lymph nodes.


Stage 4 melanoma

If melanoma is diagnosed at its most advanced stage, or if the melanoma has spread to another part of your body (metastasis) or it has come back in another part of your body after treatment (recurrent cancer), it may not be possible to cure it.

Treatment is available and is given in the hope that it can slow the growth of the cancer, reduce any symptoms you may have and possibly extend your life expectancy.

You may be able to have surgery to remove any other melanomas that have occurred away from the original site.

You also may be able to have other treatments to help with symptoms. These include:

  • radiotherapy
  • drug treatments


Radiotherapy may be used after an operation to remove your lymph nodes and it is also used to help relieve the symptoms of advanced melanoma.

Radiotherapy uses controlled doses of radiation to kill cancer cells. It is given at the hospital as a series of 10-15 minute daily sessions with a rest period over the weekend.

The side effects of radiotherapy include:

  • tiredness
  • nausea
  • loss of appetite
  • hair loss
  • sore skin

Many side effects can be prevented or controlled with medicines that your doctor can prescribe, so let them know about any you experience. After treatment has finished, the side effects of radiotherapy should gradually reduce.


Drug treatment


Chemotherapy involves using anti-cancer (cytotoxic) drugs to kill the cancer. Chemotherapy is normally used to treat melanoma that has spread to parts of the body beyond its original site. It is mainly given to help relieve the symptoms of advanced melanoma.

Several different chemotherapy drugs are used to treat melanoma and they are occasionally given in combination. The drugs most commonly used for melanoma are dacarbazine and temozolomide. However, many different types of drugs could be used. Your specialist can discuss which drugs are best for you.

Chemotherapy is usually given as an outpatient treatment, which means you will not have to stay in hospital overnight. Dacarbazine is given through a drip straight into the blood through a vein and temozolomide is given as tablets. You would probably receive chemotherapy sessions once every three to four weeks, with gaps between treatment intended to give your body and blood time to recover.

The main side effects of chemotherapy are caused by their influence on the rest of the body. Side effects include infection, nausea and vomiting, tiredness and sore mouth. Many side effects can be prevented or controlled with medicines that your doctor can prescribe.


Immunothereapy uses drugs (often derived from substances that occur naturally in the body) that encourage your body's immune system to work against the melanoma. Two such treatments in regular use for melanoma are interferon-alpha and interleukin-2. Both are given as an injection (into the blood, under the skin or into lumps of melanoma). Side effects include flu-like symptoms, such as chills, a high temperature and joint pain, and fatigue.


There is ongoing research into producing a vaccine for melanoma, either to treat advanced melanoma or to be used after surgery in patients who have a high risk of the melanoma coming back. Vaccines are designed to focus the body's immune system so that it recognises the melanoma and can work against it. Vaccines are usually given as an injection under the skin which has to be repeated every few weeks, often over a period of months. You would only have a vaccine as part of a clinical trial.

Monoclonal antibodies

Our immune systems make antibodies all the time, usually as a way of controlling infections. They are substances that recognise something which doesn't belong in the body and help to destroy it. Antibodies can be produced in the laboratory, and these can be made to recognise and lock on to specific targets, either in the cancer or in specific parts of the body. Antibodies produced in the laboratory are usually called monoclonal antibodies.
Two types of monoclonal antibodies that are currently being investigated for melanoma treatment are bevacizumab and ipilimumab.

Bevacizumab is currently licensed as a treatment for advanced bowel cancer. Research is ongoing to see if it can reduce the risk of melanoma coming back once it has been removed from the skin or lymph nodes. Your doctor can advise you whether you would be eligible to enter the clinical trial that is exploring this.

Signalling inhibitors

Signalling inhibitors are drugs that work by disrupting the messages (signals) that a cancer uses to co-ordinate its growth. There are hundreds of these signals, and it is difficult to know which ones need to be blocked. Most of the signals have short, technical names. Two that are of current interest in melanoma are BRAF and MEK. There are drugs available that can interfere with these signals, but they are only available as part of clinical trials at present.


Deciding against treatment for Stage 4 melanoma

As many of the treatments above have unpleasant side effects that can affect your quality of life, you may decide against having treatment, particularly if it is unlikely to significantly extend your life expectancy or if you do not have symptoms that are causing you pain or discomfort.

This is entirely your decision and your healthcare team will respect it. If you decide not to receive treatment, pain relief and nursing care will be made available as and when you need it. This is called palliative care.


Clinical trials

All new treatment for cancer (and for other diseases) is first given to patients in a clinical trial. A clinical trial or study is an extremely rigorous way of testing a drug in real people, with patients monitored both for an effect of the drug on the cancer and for any side effects. Many patients with melanoma are offered entry into clinical trials, but some people are suspicious of the process.

There are a few key things to know about clinical trials:

  • Overall, patients in clinical trials do better than those on routine treatment, even when they are receiving a drug that would be given routinely. 
  • All clinical trials are very highly regulated.
  • All new treatments will first become available through clinical trials.
  • Even where a new drug fails to offer any benefits over existing treatment, the knowledge that we gain from the trial is valuable for future patients. 

If you are asked to take part in a trial, you will be given an information sheet and, if you want to take part, you will be asked to sign a consent form. You can refuse or withdraw from a clinical trial without it affecting your care.


Recurring melanomas

If you have had melanoma in the past, there is a chance that the condition may return. The chance of your melanoma returning is higher if your previous cancer was particularly widespread and severe.

You also have a higher risk of developing another new melanoma or other skin cancers.

If your cancer team feels that there is a significant risk of your melanoma returning, you will probably need regular check-ups to monitor your health. You will be taught a range of self-examination techniques that you can use to check for any tumours on your skin.

It is also very important to avoid overexposure to the sun. See Melanoma - prevention for more information.

The best way to prevent all types of skin cancer is to avoid overexposure to the sun.

Avoid the sun when it is at its hottest

The sun is usually at its hottest around midday, but it can also be very strong and have potentially damaging effects at other times. Do not spend long periods in the sun during the day and make sure you spend time in the shade and cover up with clothes as well as sunscreen.

Dress sensibly

If you cannot avoid spending long periods of time in the sun - for example, if you have a job that requires you to work outside - wear clothes that will provide protection from the sun. This should include a hat to protect your face, scalp and neck and sunglasses to protect your eyes.

Use sunscreen

When buying sunscreen, make sure that it is suitable for your skin type and blocks both ultraviolet A (UVA) and ultraviolet B (UVB) radiation.

Sunscreen should be applied around 15 minutes before you go into the sun and reapplied every two hours. If you are planning to spend time in the water, use a water resistant sunscreen and be aware that no sunscreen is waterproof.

Take extra care to protect babies and children. The skin of babies and children is much more sensitive than adult skin and repeated exposure to sunlight could lead to skin cancer developing in later life. Before going out into the sun, make sure that your children are dressed appropriately and that they are wearing a hat and a high protection factor sunscreen.

Avoid burning

If you spend time in the sun, avoid getting sunburnt. Once you are burnt, the damage has already been done to your skin as your skin has received a dangerous level of radiation. Every time the skin is exposed to radiation, this increases the chance of a cancer occurring, possibly many years in the future.

Tan sensibly

Most health professionals will tell you to avoid sunbathing altogether because even a tan can increase your risk of developing skin cancer. However, if you are determined to get a tan, do it gradually by limiting the amount of time you spend in the sun each day and by wearing sunscreen. When you begin to tan, limit your exposure to the sun to 30 minutes, then gradually increase it by 5 or 10 minutes a day.

Sunbeds and sunlamps

The Irish Association of Dermatologists is Ireland's leading professional body on skincare. They recommend that people do not use sunbeds or sunlamps.

Sunbeds and lamps can be more dangerous than natural sunlight because they use a concentrated source of ultraviolet (UV) radiation.

UV radiation can increase your risk of developing melanomas - the most dangerous type of skin cancer. Sunbeds and sunlamps can also cause premature ageing of the skin.

It is even more important to avoid using sunbeds and sunlamps if you are in one of the high-risk groups for developing skin cancer (see Melanoma - causes for more information).

If you insist on using sunbeds or sunlamps,you should avoid them if:

  • You have fair, sensitive skin that burns easily or tans slowly or poorly.
  • You have a history of sunburn, particularly in childhood.
  • You have lots of freckles or red hair.
  • You have lots of moles.
  • You are taking medicines or using creams that make your skin sensitive to sunlight.
  • You have a medical condition that is made worse by sunlight.
  • You have had skin cancer or someone in your family has had skin cancer.
  • Sunlight has already badly damaged your skin.

If you use a sunbed, the operator should advise you on your skin type and on how many minutes you should use the machine for.

Content provided by NHS Choices and adapted for Ireland by the Health A-Z.

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