What is skin cancer?
Skin cancer is the most common type of cancer in the United States. An
estimated 40 to 50 percent of Americans who live to age 65 will have skin
cancer at least once. Basal cell carcinoma accounts for more than 90 percent
of all skin cancers in the United States. It is a slow-growing cancer
that seldom spreads to other parts of the body. Squamous cell carcinoma
also rarely spreads, but it does so more often than basal cell carcinoma.
Squamous cells are flat and make up most of the epidermis, the outer layer
of the skin. Basal cells are round and lie under the squamous cells.
What is melanoma?
Melanoma is the most serious cancer of the skin. In some parts of the
world, especially among Western countries, the number of people who develop
melanoma is increasing faster than any other cancer. In the United States,
for example, the number of new cases of melanoma has more than doubled
in the past 20 years. Melanoma occurs when melanocytes (pigment cells
in the lower part of the epidermis) become malignant, meaning that they
start dividing uncontrollably. If melanoma spreads to the lymph nodes,
it may also reach other parts of the body such as the liver, lungs, or
brain. In such cases, the disease is called metastatic melanoma.
What are the symptoms of skin cancer?
The most common warning sign of skin cancer is a change on the skin, especially
a new growth or a sore that doesn't heal. Both basal and squamous cell
cancers are found mainly on areas of the skin that are exposed to the
sun-the head, face, neck, hands, and arms. However, skin cancer can occur
anywhere. Often, the first sign of melanoma is a change in the size, shape,
color, or feel of an existing mole. Melanomas can vary greatly in the
ways they look, but generally show one or more of the "ABCD" features:
their shape may be asymmetrical, their borders may be ragged or otherwise
irregular, their color may be uneven, with shades of black and brown;
and their diameter may change in size.
What causes skin cancer?
Ultraviolet (UV) radiation from the sun is the main cause of skin cancer.
Artificial sources of UV radiation, such as sunlamps and tanning booths,
can also cause skin cancer. UV radiation can cause misspellings in DNA
and, as a result, damage skin cells. About 10 percent of all patients
with melanoma have family members who also have had the disease. When
melanoma runs in a family, the family members should be checked regularly
by a doctor.
Who is most at risk of developing skin cancer?
Although anyone can get skin cancer, the risk is greatest for people who
have fair skin that freckles easily-often those with red or blond hair
and blue or light-colored eyes People who live in areas that get high
levels of UV radiation from the sun are more likely to get skin cancer.
Worldwide, the highest rates of skin cancer are found in South Africa
and Australia, areas that receive high amounts of UV radiation. Skin cancer
is related to lifetime exposure to UV radiation. Most skin cancers appear
after age 50, but the sun's damaging effects begin at an early age.
How is skin cancer treated?
Melanoma can be cured if it is diagnosed and treated when the tumor has
not deeply invaded the skin. However, if a melanoma is not removed at
its early stages, cancer cells may grow downward from the skin surface.
When a melanoma becomes thick and deep, the disease often spreads to other
parts of the body and is difficult to control. Surgery is the standard
treatment for melanoma. However, if the cancer has spread to other parts
of the body, doctors may use other treatments, such as chemotherapy, immunotherapy,
radiation therapy, or a combination of these methods.
How can skin cancer be prevented?
Protection should start in childhood to prevent skin cancer later in life.
Whenever possible, people should avoid exposure to the midday sun, wear
protective clothing such as sun hats and long sleeves, and use sunscreen
lotions with an SPF factor of at least 15.
Adapted from the booklets What You Need To Know About Skin Cancer
and What You Need To Know About Melanoma, published by CancerNet, a service
of the National Cancer Institute