Cancer of the Skin

Most skin cancers begin in the epithelial cells of the skin. Skin has two layers: the top layer or epidermis and the underlying dermis. Cell division takes place in the deepest (basal) layer next to the dermis, and as cells die they are replaced by new ones.

The epidermis also contains pigment cells, called melanocytes, which produce the brown pigment melanin which is incorporated in the multiplying cells and which protects them from the damage caused by ultraviolet light. The rate of pigment production is accelerated when exposure to sunlight is increased; this is the process that produces a suntan and, when out of control, can cause a melanoma (skin cancer).

Symptoms

Skin cancer has many different appearances. It may start as a small, pale, waxy lump that eventually bleeds and crusts. It occurs mainly on sun-exposed areas, such as face, scalp, neck, hands and arms.

Then there is the melanoma which usually, but not invariably, arises in a pre-existing mole or coloured skin-patch, present since birth. The surface is uneven, it is blackish or brown, or may be mottled with shades of red and blue. Sometimes the surrounding skin may become inflamed, red and tender. It can turn into an open sore that bleeds.

Skin cancer is sometimes preceded by rough red areas of skin, usually on the face, neck, hands or legs. They are called actinic-keratoses and do not always turn into cancer. The anti-cancer ointment 5 fluorouracil is very effective in dealing with this problem.

There are two common cancers of the skin and one less common and all three are usually induced by sunlight. The first is the rodent ulcer or basal cell carcinoma which arises in the basal cell layer, does not metastasise and is, therefore, readily curable. The second, squamous carcinoma is made up of squamous epithelium and can spread to regional lymph nodes. It is also readily curable.

Finally there is the melanoma, which arises in the skin’s melanocytes and which has a tendency to spread and form distant matastases. Although still relatively rare, its incidence is steadily increasing all over the world, a high price to pay for vanity and the commands of fashion, in the form of a sun-tanned, bronzed body.

Melanoma can appear anywhere on the skin. On men it is most common on the head and neck, on women, the legs and feet. It can also begin in the eye, mouth, nose, vagina and anus.

Scandinavia now has 11 new cases of melanoma per 100,000 people each year and this figure is doubling every 10 years. Queensland, Arizona and New Mexico have 32 new cases per 100,000 and in Queensland this figure doubles every 15 years. In Arizona and New Mexico the incidence has quadrupled in the past 10 years and is entirely confined to the ‘Anglo’ population of North-European descent, sporting a fair complexion. Epidemiological evidence is building up to suggest that the rapidly increasing incidence of cutaneous malignant melanoma is related to greater exposure of white skin to strong, natural sunlight. The patient with a melanoma is, however, not the man or woman who has spent a lifetime in an outdoor occupation and who has a high total lifetime dose of natural sunlight. He or she is more at risk of developing one of the other two types of skin cancer. By contrast, the patient with melanoma is two to three decades younger and is most often an indoor office worker of high socio-economic state. There is a relationship between severe sunburn and development of melanoma in the following five years, suggesting that short periods of intense burning sunlight are a risk factor, as is exposure of areas other than face and hands, particularly in people who cannot tolerate ultraviolet light and freckle easily.

The sun emits an ultraviolet light B and, as is known, these rays produce a tan readily, but they burn first. Long-term exposure can cause premature skin ageing and tumours. The rays emitted by sunbeds are usually ultraviolet light A and these rays cause tanning without burning. So far no serious long-term effects have been reported and at this stage ultraviolet light A can be considered to be non-carcinogenic on its own. However, when used in conjunction with the sun’s ultraviolet light B, it seems that ultraviolet light A, in regular use of sunbeds, may be able to increase ultraviolet light B’s ability to promote development of non-melanoma skin-cancer, as well as of malignant melanoma

The only advantage of sunbeds is the production of vitamin D in the skin, which of course is also available in the normal diet; otherwise Lying on a sunbed, either in the short or long term is not a pastime to be encouraged. When sun-bathing, a barrier sun-lotion or sun-cream should be used, so that one can sit safely in the direct sunlight, the harmful rays having been filtered out. The cream should be re-applied at frequent intervals, particularly after swimming or when sweating hard. It is well to remember that no barrier cream is completely effective in the southern hemisphere when the sun is strongest and you should be very careful in tropical countries. This also applies to high altitudes: the higher up the more forceful the sun. As snow reflects the sun, particular care of the skin is necessary when skiing. In any case, people who are prone to sunburn should always wear a hat and a long-sleeved shirt, especially on the beach.

Treatment

Surgical removal of a malignant skin lesion is a very effective method of treatment in all three types of skin cancer. In the case of a melanoma the surgeon, however, takes an even wider margin around and underneath the tumour and sometimes even removes underlying muscle. A skin graft may have to be applied to cover the skin defect caused by the wide cut.

Where surgery is difficult or would leave an unsightly scar, radiotherapy can be used but only for a rodent ulcer or a squamous cell carcinoma. In these types of skin cancer, results of treatment are usually good. They are less so for melanoma, which frequently metastasise and thus become incurable.

Summary And Symptoms

In summary, here is a list of risk-factors contributing to the development of a melanoma, which increase with age:

1. A family history of melanoma.
2. Having previously had a melanoma.
3. Sudden appearance of a mole in fair-skinned, fair-haired people with light-coloured eyes and a tendency to sunburn easily and tan with difficulty.
4. Brown birthmarks which deepen in colour, increase in size and thickness, become irregular in shape or start to bleed.
5. A previous blistering sunburn.
6. Outdoor recreational habits in sunny regions with lengthy exposure to the sun, particularly in people with indoor occupations.