Skin cancer (Malignant melanoma)
Reviewed by Dr Dan Rutherford, GP
What types of skin cancer are there?
There are two main types of skin cancer; malignant melanoma (cancer in moles), and the non-melanoma group (basal cell and squamous cell carcinoma).
Each year approximately 1 in every 10,000 people in the UK will develop a new case of malignant melanoma. It accounts for about 1500 deaths annually in the UK.
Sun radiation is a contributing factor in 90 per cent of all cases of skin cancer.
People of all ages can get skin cancer, but it is rarely seen in children. People who are exposed to large quantities of sun radiation can develop skin cancer as early as 20-30 years of age, but the disease is much more common in elderly people.
Symptoms and treatment depend on what type of cancer it is. The female to male ratio is 2:1, and it is most commonly seen (50 per cent) on the lower leg.
What is malignant melanoma?
Malignant melanoma is a type of skin cancer that begins in the skin's 'pigmentation system', ie the skin layer that becomes tanned in the summer.
Melanomas usually start in moles or in areas of normal-looking skin. In rare cases the tumour may begin in the eyes, the respiratory passage, the intestine, or the brain.
Malignant melanoma is a very dangerous type of cancer, and the patient's chances of survival often depend on early discovery and treatment.
What causes skin cancer?
Skin cancer is caused by exposure to sunlight, particularly the ultraviolet (UV) rays, and 80 per cent of cases are therefore preventable.
The risk of developing skin cancer is increased following episodes of sunburn, although the there may be a delay of many years before the cancer appears.
A small number of cases are caused by hereditary conditions, but they are also triggered by exposure to sun rays. Sun beds can also cause skin cancer.
What are the symptoms of skin cancer?
* The colour of the tumours vary from brown or black to blue or orange.
* The tumours are characterised by having ragged edges and uneven colours.
* Off-shots, sores, crusts, and reddening may be seen in the area surrounding the mole.
* The tumour may resemble a 'blood blister' under a nail.
* The mole may itch.
* Moles can be found anywhere on the body, but are typically located on the back, the shoulders, or the back of the legs.
What are the warning signs?
* An existing mole changes in colour or shape, or begins to bleed or ooze. Sores that heal very slowly may appear on the mole.
* Moles that have become unusually large.
* 'Blood blisters' especially under toenails, that are not the result of a blow.
* The appearance of a new irregular mole (it is quite normal for people to develop new moles from time to time until they reach their 40s. There is no need to worry unless the colour of the new mole is uneven, or its edges are ragged). If you are in any doubt, ask your GP to check.
* Any unusual sore, lump or blemish lasting more than a few weeks.
* Areas of skin that become scaly, itchy, tender or red, or areas that ooze, bleed or become crusty.
What can be done to prevent skin cancer?
* Avoid excessive exposure to the sun, especially the midday sun (from 11am to 2pm).
* Move into the shadow and have a 'siesta' instead.
* Clothing and sun hats can protect the skin from the harmful rays. It is especially important to cover the skin from 11am to 2pm.
* Children must be protected from sunburn.
* Consult your doctor if you have sores that will not heal or unusual changes in a mole.
How is skin cancer diagnosed?
Skin cancer can be difficult to recognise, so a biopsy is usually performed. The tissue is then examined under a microscope.
* Some GPs can perform the biopsy in the surgery but it is usually performed by a dermatologist or a plastic surgeon.
* The doctor will also look for signs indicating that the cancer has spread to the surrounding tissue or lymph nodes.
* Skin cancer requires hospital treatment.
Future prospects
It is important that the cancer be detected as early as possible. The patient's chances of being cured largely depend on how early the treatment is started. If the disease is not treated, it will cause death.
How is skin cancer treated?
* Surgery is the standard treatment for mole cancer. The extent of the procedure is determined by the thickness of the tumour, ie how deeply it has invaded the skin.
* It is necessary to remove not only the tumour, but also some of the normal skin around it, and the fatty tissue beneath it.
If there are signs that the cancer has spread to nearby lymph nodes, these will also be removed, if it is technically possible.
* Medical treatment is used in cases where the cancer has spread to other parts of the body, and surgery is not possible. Chemotherapy and radiotherapy may also be used. These treatments are carried out by specialists in a hospital.
Based on a text by Dr Eric Olesen
Last updated 01.08.2005
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