Melanoma is a type of skin cancer -- one of the most serious types because advanced melanomas have the ability to spread to other parts of the body. (Melanoma can also develop in the eye, called intraocular melanoma, or rarely in other parts of the body where pigment cells are found. The CIS ¹ can provide information about the diagnosis and treatment of intraocular melanoma.) Melanoma begins when melanocytes (pigment cells) gradually become more abnormal and divide without control or order. These cells can invade and destroy the normal cells around them. The abnormal cells form a growth of malignant tissue (a cancerous tumor) on the surface of the skin. Melanoma can begin either in an existing mole or as a new growth on the skin. The "Pictures of Melanoma ²" section shows examples of melanoma. A doctor or nurse specialist can tell whether an abnormal-looking mole should be closely watched or should be removed and checked for melanoma cells. The purpose of routine skin exams is to identify and follow abnormal moles.

The removal of the entire mole or a sample of tissue for examination under a microscope is called a biopsy. If possible, it is best to remove moles by an excisional biopsy, rather than a shave biopsy.

If the biopsy results in a diagnosis of melanoma, the patient and the doctor should work together to make treatment decisions. In many cases, melanoma can be cured by minimal surgery if the tumor is discovered when it is thin (before it has grown downward from the skin surface) and before the cancer cells have begun to spread to other places in the body. However, if melanoma is not found early, the cancer cells can spread through the bloodstream and lymphatic system to form tumors in other parts of the body. Melanoma is much harder to control when it has spread. The spread of cancer is called metastasis.

Doctors and scientists believe that it is possible to prevent many melanomas and to detect most others early, when the disease is more likely to be cured with minimal surgery. In the past several decades, an increasing percentage of melanomas have been diagnosed at very early stages, when they are quite thin and unlikely to have spread. Learning about prevention and early detection, while important for everyone, is especially important for people who have an increased risk for melanoma. People who are at an increased risk include those who have dysplastic nevi or a very large number of ordinary moles.

Risk Factors for Melanoma Family history of melanoma Dysplastic nevi History of melanoma Weakened immune system Many ordinary moles (more than 50) Ultraviolet (UV) radiation Severe, blistering sunburns Freckles Fair skin

The National Cancer Institute booklet What You Need To Know About™ Melanoma ³ has more information about risk factors for this disease.

It is important to remember that not everyone who has dysplastic nevi or other risk factors for melanoma gets the disease. In fact, most do not. Also, about half the people who develop melanoma do not have dysplastic nevi, and they may not have any other known risk factor for the disease. At this time, no one can explain why one person gets melanoma while another does not. Research has shown that sun exposure, especially excessive exposure that leads to bad, blistering sunburns, is an important and avoidable risk factor. Scientists are continuing their studies of risk factors for melanoma.

Glossary Terms

The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue. There are many different types of biopsy procedures. The most common types include: (1) incisional biopsy, in which only a sample of tissue is removed; (2) excisional biopsy, in which an entire lump or suspicious area is removed; and (3) needle biopsy, in which a sample of tissue or fluid is removed with a needle. When a wide needle is used, the procedure is called a core biopsy. When a thin needle is used, the procedure is called a fine-needle aspiration biopsy.

A surgical procedure in which an entire lump or suspicious area is removed for diagnosis. The tissue is then examined under a microscope.

The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. This system includes the bone marrow, spleen, thymus, lymph nodes, and lymphatic vessels (a network of thin tubes that carry lymph and white blood cells). Lymphatic vessels branch, like blood vessels, into all the tissues of the body.

Cancerous. Malignant tumors can invade and destroy nearby tissue and spread to other parts of the body.

The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a “metastatic tumor” or a “metastasis.” The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases (meh-TAS-tuh-SEEZ).

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.

A procedure in which a skin abnormality and a thin layer of surrounding skin are removed with a small blade for examination under a microscope. Stitches are not needed with this procedure.

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancer), or malignant (cancer). Also called neoplasm.