Understanding Skin Cancer -- the Basics
What Is Skin Cancer?
Skin cancers involve abnormal cell changes in the outer layer of skin.
It is by far the most common cancer in the world, accounting for 75% of all cancer diagnoses. Most cases are cured, but the disease is a major health concern because it affects so many people. The incidence of skin cancer is rising, even though most cases could be prevented by limiting the skin's exposure to ultraviolet radiation.
Skin cancer is about three times more common in men than in women, and the risk increases with age. Most people diagnosed with skin cancer are between ages 45 and 54, although all forms of the disease are appearing more often in younger people. If you or any close relatives have had skin cancer, you are more likely to get the disease. Geography and race also factor into your chances of getting skin cancer, with the rate of skin cancer at its highest where fair-skinned Caucasians migrated to an area with higher annual sun exposure than their prior climates.
Every malignant skin tumor in time becomes visible on the skin's surface, making skin cancer the only type of cancer that is almost always detectable in its early, curable stages. Prompt detection and treatment of skin cancer is equivalent to cure.
Types of Skin Cancer
Skin cancers fall into two major categories: melanoma and nonmelanoma.
Melanoma can start in heavily pigmented tissue, such as a mole or birthmark, as well as in normally pigmented skin. Melanoma most commonly appears first on extremities, chest, or back, although it can occasionally arise on the palm of the hand; on the sole of the foot; under a fingernail or toenail; in the mucus linings of the mouth, vagina, or anus; and even in the eye.
Melanoma is a potentially aggressive, life-threatening cancer. It is readily detectable and usually curable if treated early, but it progresses faster than other types of skin cancer and can spread beyond the skin to affect numerous parts of the body, including the bones or brain. Once this occurs, melanoma becomes very difficult to treat and is incurable.
The two most common skin cancers, basal cell carcinoma and squamous cell carcinoma, are nonmelanomas and are rarely life-threatening. They progress slowly, seldom spread beyond the skin, are detected easily, and usually are curable. Basal cell carcinoma, which accounts for nearly three out of four skin cancers, is the slowest growing. Squamous cell carcinoma is somewhat more aggressive and more inclined to spread. In addition, there are a few rare nonmelanomas, such as Kaposi's sarcoma, a potentially life-threatening disease characterized by purple growths and associated with a suppressed immune system and almost always seen in patients with AIDS or the elderly.
Some noncancerous skin growths have the potential to become cancerous. The most common are actinic keratoses – crusty, reddish lesions that may scratch off but grow back on sun-exposed skin.