Skin cancer Totally Explained

Everything about Skin Cancer totally explained

Skin cancer is a malignant growth on the skin which can have many causes. 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. Cancers caused by UV exposure may be prevented by avoiding exposure to sunlight or other UV sources, and wearing sun-protective clothes. The use of sunscreen had been recommended in the past, but there's an increasing body of evidence that sunscreen isn't entirely safe.
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 cancers are the fastest growing type of cancer in the United States. Skin cancer represents the most commonly diagnosed malignancy, surpassing lung, breast, colorectal and prostate cancer. More than 1 million Americans will be diagnosed with skin cancer in 2008.

Risk factors

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

Overexposure to UV-radiation can cause skin cancer either via the direct− 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 - the malignant melanom.
Chronic non-healing wounds, especially burns. These are called Marjolin's ulcers based on their appearance and can develop into squamous cell carcinomaand.
Genetic predisposition, including "Congenital Melanocytic Nevi Syndrome". CMNS is characterized by the presence of "nevi" or moles of varying size that either appear at or within 6 months of birth. Nevi larger than 20 mm (3/4") in size are at higher risk for becoming cancerous. Skin can be protected by avoiding sunlight entirely, or wearing protective clothing while outdoors. Skin cancer is usually caused by exposing skin to UV rays excessively.

Types

The most common types of skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) which may be locally disfiguring but are unlikely to metastasize (spread to other parts of the body). The most dangerous type of skin cancer is malignant melanoma. This form of skin cancer is causing the major part of all skin cancer fatalities.
More rare types of skin cancer include:

Dermatofibrosarcoma protuberans

Merkel cell carcinoma

Kaposi's sarcoma The BCC and the SCC often carry a UV-signature mutation indicating that these cancers are caused by UV-B radiation via the direct DNA damage. However the malignant melanoma is predominantly caused by UV-A radiation via the indirect DNA damage. The indirect DNA damage is caused by free radicals and reactive oxygen species. It has been shown, that the absorption of sunscreen into the skin leads to an increase of free radicals in the skin.

Skin cancer as a group

Many laymen and even professionals consider the basal cell carcinoma, the squamous cell carcinoma and the malignant melanoma as one group - namely skin cancer. This grouping is problematic for two reasons:

the mechanism that generates the first two forms is different from the mechanism that generates the melanoma. The direct DNA damage is responsible for BCC and SCC while the indirect DNA damage causes melanoma.

the mortality rate of BCC and SCC is around 0.3 causing 2000 deaths per year in the US. In comparison the mortality rate of melanoma is 15-20% and it causes 138000 deaths per year. Many scientists argue that the sun-avoiding health message does decrease the less relevant forms of skin cancer and increase the incidence number of more frequently fatal melanoma.Even though it's rare, malignant melanoma is responsible for 75 % of all skin cancer related death cases. While sunscreen has been shown to protect against BCC and SCC it has also been shown to be responsible for the increase in malignant melanoma. When sunscreen penetrates into the skin it generates reactive chemicals that can damage DNA and induce melanoma. It has indeed repeatedly been found that sunscreen users are more likely to develop malignant melanoma than non-users.

Further Information

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