What is melanoma, who does it affect and how can people avoid it?

Over the past two decades, cancer cases in the UK have been rising twice as fast for people under the age of 50 compared with older age groups: almost 100 seemingly fit and healthy young adults in Britain discover they have a tumour every day.

Melanoma, is one of the three main types of skin cancer along with basal cell carcinoma – which starts in the basal cells of the lower epidermis, the outermost layer of skin – and squamous cell carcinoma, which starts in the squamous cells of the outermost layer of skin.

Melanoma is the least common of the three, but the second most common cancer detected in those in the 25 to 49 age group in the UK, affecting 3,282 young people between 2017 and 2019. It is the most deadly because it can spread to other parts of the body, but it does not have to be.

Why are so many young people being diagnosed with melanomas?

Largely because of childhood sunburn – one blistering sunburn during childhood or adolescence nearly doubles a person’s lifetime risk of developing melanoma.

Prof Paul Nathan, a consultant medical oncologist at Mount Vernon Cancer Centre, despairs every summer. “The first sunny day of the year, you see young people stripping off, going bright red and peeling,” he said.

“We need to get to a place where it’s culturally unacceptable not to use sun protective clothing, wear a hat and use sun cream.”

What should people look out for?

Every few months, look for the Ugly Duckling – the mole that is different because it is lighter, darker, bigger, smaller or on its own.

Also look for the ABCDEs: asymmetry (the two halves don’t match); border (melanomas often have uneven edges); colour (benign moles are usually a single shade of brown); diameter (if a lesion is about 6mm, get it checked out); evolving (changes in size, shape, colour or elevation; bleeding, itching or crusting).

Prof Tim Spector, who leads the UK arm of a new international team of scientists based at King’s College London, investigating rises in cancers, said more than 10 moles above 3mm in diameter on one arm suggests you need screening. This does not apply to everyone, however: “Children and people of colour do not need to be screened for skin cancer,” he said.

Do not be tempted to use AI: apps that claim to diagnose melanoma are unreliable. Instead, ask a partner to help. Take photos of moles that concern you and check back on them.

Is sunlight the main culprit?

Yes – but it’s not that simple.

Spector believes the odds of developing melanoma is largely dependent on genetics. “What isn’t talked about enough is the specific risk of staying in the sun for long periods for those with a family history of melanoma, pale skin and freckles, and those with a large number of moles,” he said.

Dr Amaya Viros, from Cancer Research UK, agreed. “It is impossible to predict what level of sun is safe for anyone, regardless of ethnicity. People have unique reactions to sunlight based on many germline factors: you might be a blonde with blue eyes and not burn – or be like me: I have brown hair, brown eyes and come from Barcelona but burn after five minutes.”

Dr Kurt Ayerst, lead dermatologist at ScreenCancer UK, said skin damage was not the whole story: there’s also the cumulative effect of radiation. “Sun exposure increases the risk of non-melanoma skin cancers,” he said.

Ayerst believes there’s no such thing as a safe tan: “Pigmentation in your skin is your body’s attempt to protect itself . But cells sped up to make more colour are also more likely to make errors – meaning they’re one step closer to becoming melanomas.”

Should we avoid the sun and wear high protection sunscreen all year round?

Some health advice recommends this – but too much shade can be harmful too: about one in five children and adults in the UK already have low vitamin D levels. Year-round use of sunscreen in the UK can lead to skin problems such as acne and peri-orificial dermatitis. There is also the issue of rising allergies to sunscreens.

Some studies show that, in people with melanoma, lower levels of vitamin D are associated with poorer outcomes and thicker tumours – a measure of disease severity.

But Dr David Robert Grimes, a scientist and author of The Irrational Ape, has said there is no evidence sunscreen inhibits vitamin D production. However, to complicate matters further, recent high-quality trials have found vitamin D supplements have no effect on mortality.

What are some of the most widespread fallacies around melanomas?

‘Melanomas are pure black with an uneven elevation and jagged outline’

Melanomas can have an uneven colour, be smooth and perfectly round.

‘Sunbathing is safe as long as you protect your moles’

About 70% of melanomas arise from normal skin – just 30% come from moles turning into melanomas. Added to which, non-melanoma skin cancers – including basal cell and squamous cell skin cancers – are predominantly caused by sun exposure. There is a high cure rate for these cancers, however: most people have minor surgery and don’t need further treatment.

‘You’re using enough sun cream’

You need a cupped handful of sun cream for an average adult body – so each tube of sun cream gives about three uses.

‘Sunbeds can be used safely’

Approximately 100 deaths a year are linked to the 28% of UK adults who use sunbeds – rising to 43% of 18 to 25-year-olds.

‘Moisturisers with SPFs give sufficient protection’

You need to wear a dedicated sun protection cream.

‘You can trust sun creams’ SPF claims’

Sun creams often over-represent their SPF. Never use any SPF lower than 30.

‘Water-resistant sunscreen is swim-resistant’

They’re not. Wear a rash vest.

‘You can reduce your risk of developing melanoma after sunburn’

You can’t. But you can learn from your mistake and not repeat it.