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 2,000 people die every year in England and Wales 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.

Outlook

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.

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 ABCDE 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.
• E stands for elevated or enlarged – the mole is raised above the surface. And it is often the case that while the original mole stays the same size the area around or under it appears to spread or swell.

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

Want to know more?

• Cancer Research UK: Melanoma symptoms.

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.

Melanomas

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.

Want to know more?

• Cancer Research UK: Melanoma symptoms.

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.

Biopsy

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 there is a concern that the cancer could have spread from the lymphatic system into other organs, bones or your blood stream, further testing will be carried out.

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, you are usually recommended to have a much bigger operation to remove all the remaining lymph nodes in the affected group. This is recommended because patients whose lymph nodes are involved and left to grow do less well than those whose affected lymph nodes are removed at an early stage. This bigger operation is often called a completion lymph node dissection or completion lymphadenectomy.

Other tests you may have include:

• chest X-ray
• magnetic resonance imaging (MRI) scan
• computerised tomography (CT) scan
• blood tests

Want to know more?

• British Association of Dermatologists: Diagnosis and staging (PDF, 96Kb).
• Cancer Research UK: Melanoma tests.

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.

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 and scalp 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 waterproof sunscreen.

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 British Association of Dermatologists is the UK'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, the Health and Safety Executive (HSE) has issued advice on the health risks linked to UV tanning equipment, such as sunbeds, sunlamps and tanning booths. They recommend that you do not use UV tanning equipment 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.

The HSE's advice also includes important points to consider before you decide to use a sunbed. For example, 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.

It is now illegal for under-18s to use sunbeds. The Sunbeds (Regulation) Act, which came into force in April 2011, prevents those under 18 from:

• being allowed to use tanning salons and sunbeds at premises including beauty salons, leisure centres, gyms and hotels
• being offered the use of a sunbed
• being allowed to be in an area that is reserved for sunbed users

Want to know more?

• SunSmart.
• HSE: Reducing health risks from the use of ultraviolet (UV) tanning equipment (PDF, 93Kb).

Kate was diagnosed with malignant melanoma after a routine check on a mole.

"I had a mole on the side of my knee which was about 1cm across," says Kate, who is 34 and lives near Glasgow. "It was a bit rough and uneven and when I saw my GP about something else, I mentioned that I wanted it removed as I didn’t like the look of it. I wasn’t worried about it, but I used to feel a bit self-conscious if I wore a skirt that wasn’t long enough to cover it. 

"At the hospital, the doctor suggested I could have a procedure where the top of the mole is shaved off under local aesthetic. No one seemed to think there was a risk of cancer, but the doctor went ahead with the procedure because of the position of the mole. After the procedure, a sample was sent off for a routine check. Two weeks later I had a message asking me to return to hospital.

"I was quite naive really and I didn’t think about why I was going back. But when I went into the clinic, I was told I had malignant melanoma and needed an operation to remove it. 

"I was totally shocked by the results. I hadn’t considered that anything like this could happen, and the fact that nobody else had thought there was cause for concern made the results even more shocking. I’m fair skinned with red hair, but I never thought I’d be at risk as I’ve never been really badly sunburnt and I’ve never used sunbeds.   

"It all happened very quickly. Two weeks after I received the results, I was given a sentinel node biopsy to see if the cancer had spread to other parts of my body. This was followed by an operation to remove the melanoma. Initially, they thought I’d need a skin graft, but luckily they managed to stitch up the 5cm incision instead. 

"It took about a month to get back to normal again. After the operation, I had to keep a splint on my leg for ten days, to keep my leg straight and give the wound a chance to heal. It was difficult waiting for the results, as it was hard not to worry that the cancer had spread. However, I was very lucky. The melanoma was self-contained.

"I have to have check-ups every three months for the first two years after the operation. I’ll then have them every six months for three more years. The nurse examines my skin and gland areas, and I also check myself at home for any changes to my skin and moles. 

"From spring onwards I wear moisturiser with a sunblock in, and during the summer I avoid the sun from 11am to 3pm. I’m careful not to spend too much time in the sun. I don’t want to risk getting burnt and doing any more damage to my skin."