Skin is the body’s largest organ. It protects against infection, stores water, helps regulate body temperature and converts sunlight into vitamin D.
Like other parts of the body, skin can be affected by cancer. The uncontrolled growth of skin cells may lead to skin cancer. Skin cancer is divided into two main groups: nonmelanoma and melanoma.
Melanoma skin cancer is less common than nonmelanoma, but it is more dangerous. When found early, it can often be treated.
Only four percent of skin cancer cases are melanomas. But melanoma accounts for almost 79 percent of all skin cancer deaths. Melanoma can spread to other organs unless it is found early and properly treated.
Melanoma comes from pigment-producing cells called melanocytes. These cells are just beneath the skin’s outer surface (epidermis). Melanocytes can break away from a melanoma tumor to grow, multiply and spread elsewhere in the body.
Cell mutations are genetic defects that may play a part in melanoma. Exposure to the sun’s ultraviolet (UV) rays is a leading factor. A lifetime in the sun, especially with sunburns early in life, can damage skin and lead to skin cancer years later.
Factors that may also influence the chance of getting melanoma include:
Fair skin or freckles.
Family or personal history of melanoma.
Chronic UV light exposure. This includes exposure to the sun and to tanning beds or sunlamps. People who live in the southern part of the U.S. or in higher elevations face higher levels of UV radiation.
Severe sunburns. Even just one severe blistering sunburn increases your risk.
Unusual moles or a large number of moles.
Weak immune system.
When to be concerned
Melanoma can start anywhere on the body. It often shows up on the upper back, torso, lower legs, arms, head and neck. A melanoma can have many different appearances. It often appears as a change in the color, size, shape or feel of a mole that you already have.
It may also begin as a blotchy, light brown, black or bluish blemish that is flat with irregular borders. As it grows, it may turn shades of red, blue or white, or have crust on the surface and flake or bleed. It may begin to itch. But often, a melanoma may not show all of these signs.
To remember the warning signs that a mole may be melanoma, use the “ABCD” rule:
Asymmetry: one half is not like the other
Border irregular: scalloped or weak border
Color varies from one area to another
Diameter larger than one-quarter inch (the width of a pencil eraser)
Melanoma is more common in fair-skinned people. It’s also seen in African Americans and dark-skinned people, often on the palms, soles of feet and under nails.
If you have a suspicious skin growth of any kind, have your doctor check it right away. There may be no other symptoms. Melanoma may not hurt or sting until it invades a nerve.
If you’ve had skin cancer, see your doctor regularly for checkups. Your doctor can make sure any skin blemishes are diagnosed and treated early.
Family doctors are trained to look for melanoma. Doctors who treat different aspects of melanoma include internists, dermatologists, surgeons and cancer specialists.