Melanoma skin cancer

Melanoma is a tumour that starts in the cells which make skin pigment. It is not the commonest skin cancer, but it is the one that readily spreads beyond the skin, and it accounts for almost all deaths from skin cancer. The saving grace is that it grows on the outside, in plain view, and at an early stage a single operation deals with it: the difference between "removed and forgotten" and months of hard treatment fits inside a short delay.

What this tumour is

The skin contains melanocytes, the cells that make melanin, the pigment that darkens skin in the sun. When a melanocyte escapes control, a melanoma forms. It can arise in a mole that was already there, but more often it appears on clear skin as a brand-new mark.

The other skin cancers, basal cell and squamous cell carcinoma, are many times more common, grow over years and almost never seed elsewhere. Melanoma is different: once it reaches a certain depth it enters the vessels and can leave deposits in lymph nodes, lungs, liver, bones and brain. A thin melanoma taken out whole, in the great majority of cases, never troubles the person again.

What a suspicious mark looks like

An ordinary mole is round or oval, evenly coloured, smooth-edged, and unchanged for years. A melanoma usually breaks at least one of those rules:

• asymmetry: fold the mark in half in your mind and the two halves do not match;
• an edge that is blurred, notched, with tongues of pigment running out into the skin;
• uneven colour, brown mixed with black, red, blue or a washed-out white;
• width over 6 mm, roughly a pencil rubber, although an early melanoma can be smaller;
• change: over a few months it has grown or altered in shape, colour or surface.

The last sign carries the most weight. A mole that is changing needs to be looked at, even if nothing else about it stands out. A second trick helps: look at all your moles together. On one person they usually resemble one another, so the one that stands apart from the crowd is worth checking. Also take seriously a mole that has begun to itch, hurt or bleed at a light touch, and a dark lengthwise band under a nail that appeared without any injury.

Melanomas that do not look like moles

The list above describes the commonest form, the one that spreads across the surface. Some melanomas do not fit it at all, and it is those forms that most often reach the doctor late.

Nodular. It grows upwards rather than outwards: a firm dome, symmetrical, all one colour, with none of the usual mottling. It develops over weeks to months, bleeds easily and ulcerates. Three words are worth remembering for it: raised, firm, growing. Any such lump that lasts beyond a month and keeps enlarging should be shown to a doctor without checking it against the rules in the previous section.

Amelanotic. A melanocyte can stop making pigment, and the tumour then looks like a pink or skin-coloured lump resembling a spot, a wart or a sore that will not heal. Any skin lesion that fails to heal is in itself a reason to be seen.

On palms, soles and under nails. This form has little to do with sunlight and occurs just as readily in people with dark skin. Warning signs are a nail band wider than 3 mm, one that widens towards the top or is unevenly coloured and, above all, pigment spreading from the nail onto the skin of the surrounding fold. A dark patch on the sole that is enlarging also needs looking at.

Away from the skin. Melanoma also occurs on mucous membranes — mouth, nose, genitals, rectum — and inside the eye. The ocular form shows itself through floaters, flashes, a missing patch of vision or a dark spot on the iris, and it is usually the optician or eye specialist who finds it.

Who is at greater risk

The main outside culprit is ultraviolet light, from the sun and from sunbeds. What counts most is not an even tan but burning to redness and blisters, especially in childhood: those episodes come back decades later. Sunbeds add risk of their own, the more so the younger someone starts using them. The rest comes with birth or with a medical history:

• fair skin that burns rather than tans, red or very blond hair, plentiful freckles;
• a large number of moles, roughly fifty upwards, and large moles of irregular shape and uneven colour;
• melanoma in a parent, brother or sister, or any previous skin cancer of your own;
• weakened immunity after a transplant or on medicines that suppress the immune system;
• a large pigmented birthmark, and rare inherited conditions with heightened sensitivity to sunlight.

Brown and black skin protects against the sun-related forms but not against the one that grows on soles and under nails, so checking feet and nails is worth everyone's while.

When to see a doctor

Book an appointment within days, rather than leaving it until after the holidays, if a mole has changed in any of the ways described above, if a new mark has not gone after several weeks, or if a dark band has appeared under a nail with no injury behind it.

Ask to be seen the same day when the lesion is visibly growing, bleeds for no reason, or has turned into a sore that will not close. This is not an emergency, but neither is it something to wait a month for.

An ambulance (112 across European countries) is for a different situation: melanoma already diagnosed and signs that other organs are involved — severe headache with vomiting, a seizure, sudden weakness of the arm and leg on one side, disturbed speech or vision, sudden breathlessness, coughing up blood.

And one rule worth knowing in advance: a suspicious lesion must never be taken off with a laser, liquid nitrogen or cautery in a beauty salon. Afterwards there is no material left to examine, and nobody will ever be able to say what it was.

How the diagnosis is made

The doctor examines not only the mark you came about but the whole skin, including the scalp, behind the ears, between the toes, the soles and the nails, and feels the nearby lymph nodes. The main instrument is the dermatoscope: a magnifying lens with a light that cancels the surface glare and reveals the pattern of pigment underneath. It is that pattern which lets a trained eye separate a harmless mole from a dangerous one; with the naked eye the difference simply is not visible. People with many moles are offered digital mapping: images of the whole skin are stored and compared at the next visit.

No blood test, ultrasound scan or CT scan finds a melanoma in the skin or proves that there is none — the diagnosis rests entirely on tissue under the microscope. The correct way to obtain it is to cut the lesion out whole, with a narrow rim of healthy skin. Shaving the top off, or taking a fragment of a large patch, is acceptable only in particular circumstances, because such a sample cannot be measured for depth. Where the change is under a nail, the sample is taken from the nail matrix. The result usually takes about two weeks.

What the report shows

The first thing looked for in the report is the thickness of the tumour in millimetres: the distance from the surface of the skin to the deepest tumour cell. That figure governs the extent of surgery, the need for further scans and the outlook. Ulceration and how actively the cells are dividing are recorded too.

If the thickness passes a certain threshold, a sentinel node biopsy is offered: the sentinel node is the first one that lymph from that area drains into. It is located with a dye or a weak radioactive tracer, removed and examined. This is not treatment but a way of finding out whether cells have travelled further.

With greater thickness, or with nodes known to be involved, ultrasound of the node areas is added, along with CT of the chest, abdomen and pelvis and often a PET scan and an MRI of the brain. The tumour tissue is tested for a mutation in the BRAF gene, which decides the choice of drug. All of it adds up to a stage from one to four: not a verdict, but the instruction on which treatment to offer.

How it is treated

Surgery is the backbone of treatment. Once the diagnosis is confirmed, the scar is excised again, taking a band of healthy skin whose width depends on the thickness of the tumour. A large defect is closed with a flap or a skin graft, and on the face a plastic surgeon is involved. Where nodes are affected, they are either removed or watched with regular ultrasound: removal often leaves lasting swelling of the limb, so the choice is discussed case by case.

When the risk of return is high, drug treatment follows surgery. Immunotherapy takes the brakes off the body's own defence cells so that they start recognising tumour cells. Targeted drugs block one specific faulty mechanism inside the cell and suit only those found to carry the matching mutation. Both are used at advanced stages as well, and it is these two that have changed outcomes in widespread melanoma over the past few years.

Radiotherapy is used selectively: to the node bed, to deposits in bone and brain, or to relieve pain. Chemotherapy has moved into the background. If the disease is widespread, the aim becomes containment: longer life and fewer symptoms. That is where the palliative care team comes in, and it is worth involving them early, alongside the main treatment rather than after it.

After treatment

Follow-up runs for several years, with a frequency set by the stage. Each visit covers the scar, the lymph drainage routes and the whole skin, because anyone who has had a melanoma carries an above-average risk of a second, separate one. Once a month it is worth checking yourself in good light, with a mirror or someone's help: back, back of the neck, buttocks, soles, between the toes.

Between visits, contact your doctor if a firm lump appears beside the scar or between the scar and the nearest group of nodes; if a node enlarges and does not settle; and also with unexplained weight loss, a persistent headache, bone pain, a long-lasting cough or breathlessness. Blood relatives are sensible to have their skin checked once and then follow the same rules themselves.

How to lower the risk

Avoiding ultraviolet altogether is neither possible nor necessary; burning is the thing never to do. The harshest radiation falls around the middle of the day, and those are the hours to spend in the shade. A guide without a clock: if your shadow is shorter than you are, the sun is dangerous.

Clothing protects better than any cream — close-woven fabric, long sleeves, a brimmed hat covering ears and neck, sunglasses with an ultraviolet filter. Sunscreen comes after that, not instead of it: broad spectrum, factor 30 or above, applied before going out and applied generously. Most people put on half of what is needed, so the real protection falls short of the number on the bottle; reapply every couple of hours and after swimming.

Sunbeds are worth ruling out entirely: there is no safe dose, and a tan is nothing other than the skin's response to damage. Children, and babies above all, need the strictest care: a back burnt in childhood affects the risk for the rest of a life.

Online consultation

An online appointment is well suited to the first question: whether a particular mark should worry you and how quickly a face-to-face examination is needed. Take several photographs beforehand in daylight, without flash, close up and with a ruler or coin alongside for scale; if you have older pictures of the same spot, send those too, since change shows up precisely in comparison.

It is useful after diagnosis as well: going through the pathology report, understanding what thickness and stage mean, preparing questions for the hospital visit, discussing side effects of treatment and the follow-up plan. The limits matter: a photograph cannot confirm or rule out a diagnosis, and a conversation is no substitute for dermatoscopy and examination of tissue.

This material is for information only and does not replace medical advice.