The three most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma, each of which is named after the type of skin cell from which it arises. Skin neoplasms are growths 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. 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. In fact, though it can be disfiguring, except for melanoma, skin cancer is rarely fatal. Skin cancer represents the most commonly diagnosed cancer, surpassing lung, breasts, colorectal, and prostate cancer.
Melanoma is less common than basal cell carcinoma and squamous cell carcinoma, but it is the most serious—for example, in the UK there are 9,500 new cases of melanoma each year, and 2,300 deaths. It is the most common cancer in the young population (20 – 39 age group).
Most cases are caused by long periods of exposure to the sun. Non-melanoma skin cancers are the most common skin cancers. The majority of these are basal cell carcinomas. These are usually localized growths caused by excessive cumulative exposure to the sun and do not tend to spread.
Ultraviolet (UV) light exposure, most commonly from sunlight, is overwhelmingly the most frequent cause of skin cancer.
Other important causes of skin cancer include the following:
- Use of tanning booths
- Immunosuppression-impairment of the immune system, which protects the body from foreign entities, such as germs or substances that cause an allergic reaction. This may occur as a consequence of some diseases or can be due to medications prescribed to combat autoimmune diseases or prevent organ transplant rejection.
- Exposure to unusually high levels of x-rays
- Contact with certain chemicals-arsenic (miners, sheep shearers, and farmers), hydrocarbons in tar, oils, and soot (may cause squamous cell carcinoma)
The following people are at the greatest risk:
- People with fair skin, especially types that freckle, sunburn easily, or become painful in the sun
- People with light (blond or red) hair and blue or green eyes
- Those with certain genetic disorders that deplete skin pigment such as albinism, xeroderma pigmentosum
- People who have already been treated for skin cancer
- People with numerous moles, unusual moles, or large moles that were present at birth
- People with close family members who have developed skin cancer
- People who had at least one severe sunburn early in life
Basal cell carcinomas and squamous cell carcinomas are more common in older people. Melanomas are more common in younger people. For example, melanoma is the most common cancer in people 25-29 years of age.
