There are cancers and cancers. Breast and cervical cancers cause serious distress and anxiety, but thanks to screening and massive publicity, we feel we know the size and shape of the enemy we're up against. Prostate cancer is the one nobody talks enough about, and the one too many men try to pretend couldn't happen to them. Lung cancer is every smoker's secret dread. Melanoma is the inscrutable cancer - creeping up on you in the guise of a slightly odd-looking mole, very treatable and yet one of the main causes of death in young men and women.
The problem for those who treat malignant melanoma is that it's got caught up in nanny-statism. It's the dire penalty that all those safe sun messages warn of - all those diatribes about covering up and using high factor sunscreen that the vast majority of the population ignores. When sun comes to shade, the hedonist in us, suppressed all the long winter, wins out. And so we don't want to know how a sun-activated mole can kill us. It doesn't even sound likely.
Yet 1,500 people die of malignant melanoma every year in the UK. It affects one in 150-200 people here.
These numbers could be down to those taking holidays in the tropics or immigrant Australasians. It is not the only form of skin cancer - there are two others (basal cell and squamous cell carcinomas) but they are unlikely to kill you. Of the 40,500 cases of skin cancer a year in the UK, 6,000 are malignant melanomas. Caught at an early stage, there's no problem, but left too long, death is almost inevitable.
Is it caused by over-exposure to the sun? The sun is certainly a factor and babies and children who are allowed to burn are especially vulnerable and could be prey to melanoma in later life. But the number of cases has doubled in the past 10 years, so sun-worship is unlikely to be the only cause. What else might be at work is unknown, although there are suspicions that it is environmental.
Melanoma occurs when the pigment cells, called melanocytes, which are plentiful in the lower part of the epidermis (the outer layer of skin) become malignant. The vast majority of melanomas occur in the skin, but they can very rarely develop in the eye, the brain or the digestive tract. Melanomas tend not to develop in dark skins, although they can occur under the fingernails or toenails, on the palm or the underside of the foot where there is less pigment.
While the melanoma is on the surface of the skin, it is relatively easy to treat. It shows up in a new, blackish or strange looking mole or in an old one that has begun to change. The mole can be surgically removed and the threat of cancer is gone - although there is a chance it will recur elsewhere. But if the malignancy is allowed to develop, the cancerous cells will spread to enter the bloodstream or the lymphatic system. "Once melanoma has spread to the lymph nodes, which drain toxins from the skin, it is more often going to cause death than not," says Elaine Rankin, Imperial Cancer Research Fund professor of cancer medicine at Dundee University.
She says people often do not realise what is happening. "If you get a mole that is bleeding, generally you assume you hit it in the garden or got scratched while playing with the children," she says. The people least likely to go to the doctor when they see an unexplained change in their skin are elderly men, she says. Melanoma kills more elderly people than any other group, but it is normal for cancers to kill older people. The difference with melanoma is that it is one of the commonest causes of death in men and women under the age of 45.
Some people are more at risk than others. "There are people with certain skin types - fair-haired people who go red in the sun and particularly redheads from the Celtic fringes, but occasionally melanoma runs in families where we know it is related to genes and they tend to be kept under fairly close observation. Melanoma, if you take it out fairly early when it is still thin, is not fatal."
Some people with a family history of the disease have a number of odd-looking moles, called dysplastic nevi. "They tend to be a lot bigger and irregular," said Professor Rankin. "The majority of people with strange-looking moles will be fine, but if there is a strong family history and more than two people in the immediate family who have had melanoma, it is good practice to get every body in the family to see a dermatologist at regular intervals."
It is changes in the moles that the dermatologist will look for, and the arrival of new ones after the teenage years. Computerised digital photographs are used to detect whether there is a difference from the way the mole looked six months or a year earlier. If there are suspicions, the mole can be surgically removed, and these days the job can be done so neatly that there is barely a mark. For those of us who do not have a family history, she says, the main things to look out for are changes in the colour and size of moles and any sign that they are becoming more irregular in shape. "It is worth looking at your moles and if you notice changes, going to your doctor," says Rankin. "Nine times out of 10, it is probably nothing."
But prevention is the current philosophy, and avoidance of the sun is a big part of that. The Australians have their "slip, slap, slop" campaign, which has had considerable success in promoting the use of high-factor sun screens, hats and T-shirts on the beaches. The UK has a long way to go. Look at the parks on sunny days. Look at the women with bare legs and hitched-up skirts and men with their shirts off. And what are the most common sites for malignant melanomas? The legs in women and the torso in men.
