Noticed any new or unusual freckles, moles, sores or sunspots on your skin lately? They may be skin cancers. Melanoma is the third most common cancer in Australia, certainly something to take seriously when you're sunning yourself on the beach this summer.

The sunburnt country

Skin cancer is the commonest form of cancer in western societies where light coloured skin and outdoor lifestyles dominate. It's not surprising the incidence of melanoma is so high in a country such as Australia - with a history of fun in the outdoors, and a population of primarily Anglo Saxon extraction. We simply aren't meant to spend a lot of time unprotected in the sun. Australia has the highest rate of skin cancer in the world - two out of three of us will develop some form of it in our lifetime.

The Skin

The skin has many important functions. It protects us from injury and attack by parasites, cools us when we get too hot and prevents us from becoming dehydrated. The skin has two main layers. The top layer is called the epidermis. This layer contains, among other things, cells that produce melanin, the substance that gives skin its colour. The layer underneath the epidermis is called the dermis. The dermis contains the roots of hairs, glands which make sweat and oil, blood and lymph vessels and nerves.

Skin Cancer

Like all body tissues, the skin is made of tiny 'building blocks' called cells. These cells can sometimes become cancerous, such as when they are exposed to ultraviolet (UV) radiation. The epidermis contains three different types of cells: squamous cells, basal cells and melanocytes. Skin cancers are named after the type of cell they start from. The three main types of skin cancer are basal cell cancer, squamous cell cancer and - the most serious skin cancer - melanoma.

Types of Skin Cancer

Early melanoma is completely curable. If melanomas of this type are diagnosed early, minor surgery is all that is required to alleviate the problem.

Superficial spreading melanoma is the most common type of melanoma, it spreads across the skin and is only dangerous when it invades deeper.

Nodular melanoma is the most dangerous form of melanoma, arising as a small lump on pure melanoma tissue in the skin. The risk of death from this type of cancer increases rapidly as it buries deeper into the skin.

Basal cell carcinoma is the commonest form of skin cancer. Beginning as a small ulcer or a small nodule of greyish tissue, usually on exposed areas of skin, it is easily treated and totally curable unless ignored.

Squamous cell carcinoma is less common than basal cell carcinoma, but more common than melanoma, this cancer is most closely related to sunlight exposure. It is usually curable with simple surgery provided it is not ignored.

Acral lentiginous melanoma occurs on the thickened skin of the soles of the feet and the palms of the hand, as well as under the nails. This is the commonest form of melanoma in people with darker skin.

Lentigo maligna melanoma (Hutchinson's melanotic freckle melanoma) occurs in pigmented patches mostly on the face and upper body, where sunlight exposure is greatest. It grows slower than other forms of melanoma, but it eventually becomes just as dangerous if not effectively treated.

Dysplastic naevus (atypical mole) are irregular in shape and have variable pigmentation. They must be watched for change.

Keratotic skin (sunspots)is the commonest evidence of sun damage to the skin. The spots are not malignant but require simple skin treatment.

The real problem with skin cancer

Often it is not the cancerous cells in our skin which cause the most damage to our health. If caught early enough 95 per cent of skin cancers are completely curable. The major complications occur when cancer cells break off from the main tumour and invade the lymphatic system.

The lymph nodes are essentially the body's garbage removal system - clearing foreign invaders, dust and other debris from the body with the aid of immune cells. Unfortunately the lymph system doesn't recognise dangerous cancer cells. They are left to spread from one cell to another, eventually entering the blood system and attacking bodily organs. When skin cancer progresses to this stage there is only a forty per cent chance that the patient will survive. Cancer suffers who have progressed to this stage require major lymphatic surgery.

An Australian breakthrough?

Until recently it was standard surgical practice to remove a section of lymph tissue containing as many as 30 lymph nodes for testing, a so-called block dissection. The damaged vessels often don't grow back, leaving patients with a condition know as lymphoderma. Awful swelling, stretched skin, pain and infection often result.

However, a new test pioneered by surgeons at Sydney's Royal Prince Alfred Hospital may mean that the chances of survival are greatly improved for suffers of rapidly progressing skin cancer. An imaging technique using a radioactive tracer chemical means that doctors are able to pinpoint cancerous lymph nodes with much greater accuracy, often only removing one or two. While this is good news for cancer sufferers it is still important to note that it will probably only increase skin cancer survival rates by about five per cent.

The old adage

As the cliche goes - prevention is better than cure. It's important to protect yourself from the sun as much as possible all year round, particularly in a climate like Australia's. Sunscreen with an SPF factor of 15 plus(preferably endorsed by the Cancer Council), protective hats, sunglasses and clothing are all essential items this summer.

And if you really feel that a tan is an absolute must, there's no need to feel bad about faking it.