Your Health A-Z

Skin cancer: why spots may be worse than moles

A new study* shows that 70% of melanoma cases originate from new spots that appear on the skin, rather than moles that become irregular – and catching them early is your best chance of beating this fast-growing and life-threatening skin cancer.

Ever look at an unfamiliar spot or blemish and wonder if it’s a blackhead, pimple – or something more? Contrary to what many people believe, most melanomas arise ‘de novo’ – ‘anew’ or ‘from the beginning’ – and only a minority arise in conjunction with existing moles.

‘In general, 20-30% of melanomas arise from existing moles present on the body, with approximately 70% of melanomas forming in skin that looks normal until the melanoma occurs,’ says dermatologist Dr Dilshaad Asmal. ‘The de-novo melanoma is more likely to appear in middle age, and on the arms, legs, head and neck.’ She also notes that melanomas can appear on skin not normally exposed to the sun, and that women have a better survival rate from de-novo melanoma than men ‘but there is no understanding why this is so’.

Dr Asmal advises that you subject a questionable blemish to the ‘ABCDE’ test: check if the spot is Asymmetrical, if it has uneven Borders, if it is more than one Colour (brown, black, blue, red or grey), if its Diameter is larger than 7mm, or if it has Evolved (changed) over time.

She also advises not to ignore any new lesions appearing on the skin. ‘Any skin growth that is new, is changing or won’t go away warrants a visit to the dermatologist,’ she says.

What is a melanoma?

Melanoma is a cancer of the skin. It begins in the melanocytes – the cells that produce the pigment melanin, which colours the skin, hair and eyes. (Melanocytes also form moles.)

This skin cancer can grow quickly and become life-threatening in as little as six weeks; if untreated, it can spread to other parts of the body (liver, lungs, bones, brain) and it is then very difficult to treat.

It is usually flat with an uneven, smudgy outline, and may be blotchy and show more than one colour.

The other skin cancers

Basal cell carcinoma: This common skin cancer – one in five people will have it in their lifetime, according to the American Skin Cancer Foundation – can often start as a small pink bump that looks like acne. It grows slowly, usually on the head, neck and upper torso, and as it grows, it may ulcerate or appear like a sore that does not heal properly.

Squamous cell carcinoma: Less lethal than other kinds of skin cancer, and more common, squamous cell carcinoma is highly treatable when detected early. It grows over some months and appears on skin most often exposed to the sun. Possible signs include a pink or white bump; a rough, scaly patch that bleeds easily; or a sore that won’t heal.

Dr Asmal emphasises the importance of prevention when it comes to skin cancer. ‘The Australian campaign of Slip, Slop, Slap is a great one: slip on a shirt, slop on sunscreen and slap on a hat. And put on sunglasses to protect your eyes.’

When it comes to sunblock, she says to check:

  • What kind? ‘Use a broad-spectrum sunblock that has both UVA and UVB protection.’
  • How much? ‘The equivalent of a shot-glassful on your body and a teaspoon on your face.’
  • How long? ‘Apply it about 20 minutes before you go into the sun to give the active ingredients time to sink in.’
  • How reliable? ‘No sunscreen product protects completely – wear UV-treated clothing and a hat too.’
  • No-no times? ‘Don’t go into the sun at all between 11h00 and 14h00.’
  • Storage? ‘The active ingredients in sunscreen lose potency, so don’t use any that are beyond their expiry date.’

References:

*http://www.jaad.org/article/S0190-9622(17)32051-0/fulltext

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