by Judy Evans

Created on: December 19, 2010   Last Updated: December 20, 2010

Skin cancer is the most common form of human cancer. In 2008, worldwide there were over 197,000 new cases of malignant melanoma and around 46,000 deaths with the highest rates occuring in Australia and New Zealand.

The most common cause is exposure to ultraviolet (UV) radiation from the sun. Ultraviolet rays are of two types – UVA and UVB. UVA rays cause long-term damage to the skin. They are more plentiful than UVB, can penetrate glass, are always present and penetrate deep into the layers of the skin.

UVB rays cause skin cancer and cataracts. They are responsible for sunburn and tanning, and help the body manufacture Vitamin D. UVB rays are more intense during summer, at high altitudes, during the middle of the day and near the equator.

Skin cancer (also known as skin neoplasia) refers to one of three conditions.

*  Non-melanoma skin cancers can be:  
Basal call carcinoma (BCC)
Most common form (75%) which rarely metastasizes (spreads) but can grow and invade surrounding tissue. Such growths on the face can be highly disfiguring.

or
Squamous cell carcinoma (SCC)
Occurs more rarely than BCC. Those with lighter skin and a long history of exposure to the sun are more predisposed to this type. It affects more men than women. In its early form (actinic keratoses), the disease appears as rough red bumps on the backs of the hands, the face, ears and scalp.

*  Melanoma
Generally the most serious form as it has a tendency to metastasize quickly throughout the body. It begins in skin cells (melanocytes) which produce a pigment (melanin) responsible for the skin colour. A mole is a cluster of melanocytes.

Warning signs
The most common warning sign is a new growth, unusual freckle, mole, sunspot or a non-healing sore.  Any changes in skin appearance should also be investigated.  

USA Cancer statistics
New cases per annum of non-melanoma skin cancers: 2.8 million BCC, 700,000 SCC (second most common form of skin cancer)
New cases pa. of melanoma skin cancers:  68,700 (accounts for 3% of diagnoses but 75% of deaths)
Skin cancer is the most common type of cancer in the USA
Over 20 Americans die daily from skin cancer with one in five likely to develop the condition.
Source: Skin Cancer Foundation

Australian Cancer statistics
New cases per annum of non-melanoma skin cancers: 434,000
New cases pa. of melanoma skin cancers:  10,300
(4th most common cancer)(most common cancer in people 15 to 44 years)

Australia has an incident rate almost four times

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