What You Need To Know About Melanoma Cancer

Melanoma* is the most serious type of
cancer of the skin. Each year in the United States, more than 53,600 people
learn they have melanoma.

In some parts of the world, especially among Western countries, melanoma is
becoming more common every year. In the United States, for example, the
percentage of people who develop melanoma has more than doubled in the past 30
years.

The National Cancer Institute (NCI) has written this booklet (NIH Publication
No. 02-1563) to help people with melanoma and their families and friends better
understand this disease. We hope others will read it as well to learn more about
melanoma. This booklet discusses risks and prevention, symptoms, diagnosis,
treatment, and followup care. It also has information about resources and
sources of support to help patients cope with melanoma.

Research continues to teach us more about melanoma. Scientists are learning
more about its causes. They are exploring new ways to prevent, find, and treat
this disease. Because of research, people with melanoma can look forward to a
better quality of life and less chance of dying from this disease.

Information specialists at the NCI’s Cancer Information Service at
1-800-4-CANCER can answer questions about melanoma and can send NCI materials.
They can also send up-to-date treatment information from NCI’s PDQ® database. In
addition, many NCI publications and fact sheets are on the Internet at
http://cancer.gov/publications. People in the United States and its territories
may use this Web site to order publications. This Web site also explains how
people outside the United States can mail or fax their requests for NCI
publications.

*Words that may be new to readers appear in italics. The Dictionary
section explains these terms. Some words in the Dictionary have a “sounds-like”
spelling to show how to pronounce them.

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What Is
Melanoma?

Melanoma is a type of skin cancer. It begins in cells in the skin called melanocytes. To understand melanoma, it is helpful to
know about the skin and about melanocytes—what they do, how they grow, and what
happens when they become cancerous.

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The Skin

The skin is the body’s largest organ. It
protects against heat, sunlight, injury, and infection. It helps regulate body
temperature, stores water and fat, and produces vitamin D.

The skin has two main layers: the outer epidermis and the inner dermis.

• The epidermis is mostly made up of flat, scalelike cells called squamous cells. Round cells called basal cells lie under the squamous cells in the
  epidermis. The lower part of the epidermis also contains melanocytes.

• The dermis contains blood vessels, lymph
  vessels, hair follicles, and
  glands. Some of these glands produce sweat,
  which helps regulate body temperature. Other glands produce sebum, an oily substance that helps keep the skin from
  drying out. Sweat and sebum reach the skin’s surface through tiny openings
  called pores.

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Melanocytes and
Moles

Melanocytes produce melanin, the pigment
that gives skin its natural color. When skin is exposed to the sun, melanocytes
produce more pigment, causing the skin to tan, or darken.

Sometimes, clusters of melanocytes and surrounding tissue form noncancerous growths called moles. (Doctors also call a mole a nevus; the plural is nevi.) Moles are very common. Most
people have between 10 and 40 moles. Moles may be pink, tan, brown, or a color
that is very close to the person’s normal skin tone. People who have dark skin
tend to have dark moles. Moles can be flat or raised. They are usually round or
oval and smaller than a pencil eraser. They may be present at birth or may
appear later on—usually before age 40. They tend to fade away in older people.
When moles are surgically removed, they normally do not return.

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Understanding
Cancer