Skin cancer is a malignant growth on the skin which can have many causes. The most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma. Skin cancer generally develops in the epidermis (the outermost layer of skin), so a tumor is usually clearly visible. This makes most skin cancers detectable in the early stages. There are three common types of skin cancer, each of which is named after the type of skin cell from which it arises. Unlike many other cancers, including those originating in the lung, pancreas,
and stomach, only a small minority of those afflicted will actually die of the disease. Skin cancer represents the most commonly diagnosed malignancy, surpassing lung, breast, colorectal and prostate cancer. Melanoma is one of the most common skin cancers and it is potentially the most serious: there are over 8,000 new cases each year in the UK and 1,800 deaths. More people now die of Melanoma in the UK than in Australia. It is the second most common cancer in the young population (20 – 39 age group). It is estimated that approximately 85% of cases are caused by too much sun. Non-melanoma skin cancers are the most common skin cancers. The majority of these are called Basal Cell Carcinomas. These are usually localised growths caused by excessive cumulative exposure to the sun and do not tend to spread.

Risk factors

Skin cancer is most closely associated with chronic inflammation of the skin. This includes:

1. Overexposure to UV-radiation can cause skin cancer either via the direct DNA damage or via the indirect DNA damage mechanism. UVA & UVB have both been implicated in causing DNA damage resulting in cancer. Sun exposure between 10AM and 4PM is most intense and therefore most harmful. Natural (sun) & artificial UV exposure (tanning salons) are associated with skin cancer. Since sunbeds cause mostly indirect DNA damage (free radicals) their use is associated with the deadliest form of skin cancer, malignant melanoma.
   1. UVA rays affect the skin at a deeper level than UVB rays, reaching through the epidermis and the dermis to the hypodermis where connective tissues and blood vessels are located. UVA activates the melanin of the epidermis causing changes in pigmentation as well as loss of elasticity of the skin, which contributes to premature wrinkling, sagging and aging of the skin.
   2. UVB rays primarily affect the epidermis causing sunburns, redness, and blistering of the skin. The melanin of the epidermis is activated with UVB just as with UVA; however, the effects are longer lasting with pigmentation continuing over 24 hours.

   Many believe that skin cancer can be prevented altogether by avoiding sunlight entirely, or wearing protective clothing while outdoors. However, studies show that Melanoma Skin Cancer is more common in those who work indoors. Skin Cancer is most common on areas of the body that are not normally exposed to the sun, and then exposing the skin to UV rays excessively.

   Skin cancer generally has a 20- to 30-year latency period. Many instances of skin cancer in older individuals today can be traced to behaviours as young adults in the 1970s and early 1980s. Deep tans at that time were routinely spoken of as "healthy." Sunburns represented an inconvenient rite of spring or an awkward preliminary stage in the process of acquiring a "healthy" tan. Severe burns were commonplace. Today we know the approach to be reckless. The incidence rates of skin cancer today in persons over 50 years of age reflect that day's popular ignorance.

   Types

   The most common types of skin cancers are:

   • Basal Cell Carcinoma
   • Squamous Cell Carcinoma
   • Melanoma
   
   

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