A mole can be a harmless spot on your skin or a sign of skin cancer. But how can we tell whether this common blemish is something we should be talking to our doctor about? Heather Stephen finds out. 

Moles are made up of cells called melanocytes which produce colour in your skin. We may be born with them although most develop during the first 30 years of life.

Most moles are innocent but they can develop into melanoma. Around 13,500 people are diagnosed with this serious skin cancer in the UK each year and it is now the nation’s fifth most common cancer.

Your risk of developing melanoma rises if you have a lot of moles, especially if they are over 5mm in diameter or have an irregular shape. One unusually shaped or very large mole, known as an atypical naevi, can increase the chance of developing melanoma by 60 per cent and having five or more of these moles makes you 10 times more likely to get it.

‘No-one knows why having lots of moles is a risk factor for skin cancer. It may just be that it is more difficult to keep a check on them and spot any changes,’ says consultant dermatologist Anton Alexandroff.

Benign or non-cancerous moles are often medium to dark brown and tend to be circular or oval with a smooth edge. But they may also be darker or skin coloured and can be flat, raised, smooth or rough.

And as moles are affected by hormones they may get darker in pregnancy, increase in number when you are a teenager and start to disappear when you go into your 40s.

So with all these variations and changes how do you know when your moles should give you concern?

Doctors advise getting into the habit of checking your skin for changes once a month as most skin cancers can be cured if detected early.

And as most melanomas are caused by ultraviolet light damage to the DNA in your skin cells experts say your best protection is to cover up in the sun and stay away from sunlamps and tanning beds.

Moles you should speak to your doctor about urgently include:

• Ones with three or more different shades of brown or black as benign moles only have one or two colours
• An uneven or ragged edge
• Bleeding, itching, redness, inflamed or crusty moles
• Moles that have increased in size and are bigger than the width of a pencil
• Moles where one side looks different to the other.

And you should also see your GP straightaway if you have a dark area under a nail that is getting bigger which is not due to an injury.

Although, everyone has a chance of developing melanoma you are most at risk if you have pale skin, red or blonde hair, blue or pale eyes, lots of freckles, are older or have had sun burn. People with these traits should be particularly vigilant about checking their skin.

Moles can happen anywhere on the body but are most common on your back, legs, arms and face.  And doctors stress that melanoma can appear on any part of your skin and is not just associated with changes to moles.

‘There’s no good evidence to suggest that removing normal moles will reduce a person’s risk of melanoma, and not all melanomas start from moles,’ says Dr Rachel Orrit, health information officer at Cancer Research UK. ‘In fact, one recent study showed only around half of melanomas developed from existing moles.

‘It’s important to get to know your body and be aware of any unusual changes to a mole or patch of skin,’ says Dr Orrit.

If you are found to have melanoma most people are cured by surgery and even patients with advanced melanoma have been shown to respond well to immunotherapy – a drug which stimulates the immune system to attack the cancer.

‘Immunotherapy is offered routinely to patients whose melanoma has spread,’ says Dr Alexandroff.  ‘The treatment has been shown to prolong life and in some cases it has appeared to cure the cancer altogether.’

But although treatments are more sophisticated Dr Alexandroff says it is still better to take steps to avoid melanoma rather than go through the trauma of treatment.

‘The best thing you can do is not to get to this stage,’ he says. ‘You need to have sunlight to process Vitamin D but be sensible. Wear factor 50 sunscreen and wide brimmed hats and stay out of the sun between 11am and 3pm and you will be doing the right things to reduce your risk of melanoma.’

Online help

• For more information about melanoma and to view images of abnormal moles go to www.cancerresearchuk.org
• More cancer facts and sun safety tips are available at the British Skin Foundation site www.ittakesseven.org.uk/skin-cancer-facts
• Dr Alexandroff  has clinics at Leicester Spire, Leicester Nuffield, Cambridge Nuffield and Bedford BMI hospitals. www.alexandroff.org.uk