Training and working as a nurse in London for nearly eight years, John Wilson thought he had seen his fair share of strange lumps and moles.

But it wasn’t until, in 2014, his GP pointed out an oddly shaped mark on his back that the then 30-year-old realised he had missed a key red flag for skin cancer on himself.

John’s doctor took a small shaving of the mole – large, black, with jagged edges and hidden just under his right armpit – and tested it on the spot. By the next day, he had a diagnosis: Melanoma, the deadliest form of skin cancer.

The disease was in the earliest stages, and, thankfully, John’s doctors removed it that day.

But the experience totally changed his attitude towards his future. ‘It was a massive shock to get a diagnosis like that – and I was so grateful to that GP for noticing it,’ said John.

‘After the cancer was removed, I made the decision to just get out and live my life.’ Over the next decade, John worked as a nurse across the world – treating disadvantaged communities across Australia and Asia, as well as sailing the Atlantic.

Then, this year, in January, just weeks after moving back to London, John found himself in hospital again, this time with a suspected kidney stone.

Training and working as a nurse in London for nearly eight years, John Wilson thought he had seen his fair share of strange lumps and moles

But when John’s doctors looked at the CT scan to confirm the diagnosis, they also found what looked like a tumour in his liver. After more scans, John and his partner Felicia were given devastating news. His cancer had returned – this time spreading to his lungs, liver, kidney and abdominal wall.

John was stunned. He had no new skin changes and felt completely fine – other than being more tired than usual, which he put down to the stresses of the move.

‘It was like a sledgehammer to the face,’ said John, but he added: ‘I was insanely lucky to have had that kidney stone, or I could have gone on for months, or even years, more without knowing.

‘I was a nurse and didn’t recognise the symptoms or signs of skin cancer, either time. Members of the public without medical training have even less of a shot. We need better awareness around the signs of melanoma.’

Diagnoses of skin cancer have climbed significantly in Britain over the past decade, with cases of melanoma rising by almost a third. Today, there are around 21,000 new cases of melanoma every year and nearly 2,300 deaths – making it one of the most common cancers in the country.

The main symptom is any new or changing growth. This can include moles that change in size, shape or colour, or that develop jagged, irregular borders. Skin cancers can also look like persistent sores that bleed, itch and crust, or unusual waxy, scaly bumps. Nine out of ten cases are considered avoidable, with exposure to ultraviolet rays from the sun – or sunbeds – being the leading cause of the disease.

And the condition is more common in men than women – with cancers tending to appear on the torso or neck of the former, and lower limbs of the latter.

Experts say that skyrocketing cases are likely to be due to a combination of factors, including an ageing population and improved diagnostics, as well as the increasing popularity and affordability of foreign holidays and outdoor sunbathing.

When John’s doctors looked at the CT scan to confirm the diagnosis, they also found what looked like a tumour in his liver. His cancer had returned – this time spreading

Yet, despite widespread alarm over the rise in skin cancer, many Britons are still unaware of the risks and signs of the disease.

A survey published earlier this year by charity Melanoma Focus revealed that one in nine British adults have deliberately burnt their skin – putting them at a heightened risk of melanoma.

The survey of more than 3,000 adults in the UK found that an astonishing one in three adults also admitted to never using sunscreen.

Health Service advice is to always use suncream with an SPF of at least 30, applying six to eight teaspoons to the entire body every two hours – and always after swimming, sweating or towelling dry.

Most melanomas are spotted because they appear as a new mole, or a change in an existing one – usually in areas exposed to the sun, says Dr Christopher Rowland Payne, consultant dermatologist at The London Clinic.

Caught early, melanoma is almost always curable – but it becomes far harder to treat over time.

Signs that the cancer has spread can be wide ranging – and depend on the organ or organs affected – but common symptoms can include hard lumps under the skin, swollen lymph nodes, persistent fatigue and unexplained weight loss.

The chance of a stage 1 melanoma that has been removed recurring is generally low. John believes he was simply unlucky.

Anyone who has had cancer who notices a change in their energy levels, weight or any new lumps and bumps should see their GP about it, advises Dr Rowland Payne. But the best way to avoid skin cancer, he advises, is to limit sun exposure in the first place.

Now having an immune-boosting treatment, John says his diagnosis has once again given him a new sense of what he wants to do next.

Studying for a qualification in dermatology, he hopes to one day train others to spot signs of skin cancer and give free mole checks through his charity Spot It Early.

‘I want to use what I’ve learned, and what I’m going through, to make a difference for others,’ he said. ‘The difference between early and late can be everything. I know that better than anyone.’

  • John is raising money for his charity on GoFundMe at www.gofundme.com/f/nurseskincancer