Cancer InDepth: Melanoma
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Skin cancers can be divided into two general categories: carcinomas (basal cell and squamous cell) and malignant melanomas. The following article is devoted to melanoma. While carcinomas are far more common than melanomas, they are generally benign in their behavior and readily respond to treatment.
Melanoma is skin cancer of the melanocytes, which are the cells that produce skin color and give moles their dark color.
The skin serves as a barrier to protect internal organs and tissues from infections and to maintain normal fluid balance. The skin helps regulate body temperature and communicates sensations such as pain or touch to the brain.
Melanocytes are found within the skin. They produce melanin, which gives the skin a tan and protects deeper layers of skin from the damaging effects of the sun. Melanoma occurs when these cells grow out of control. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which may invade nearby tissues and may spread to other parts of the body. A benign tumor does not spread.
Moles are collections of melanocytes. Normally, moles are benign. Sometimes, however, a mole can develop into melanoma. A new mole may also be an early sign of melanoma. The disease typically starts in the skin, but it also may arise in other areas where melanocytes are found, such as the eyes or the digestive system.
The three major types of skin cancer are basal cell, squamous cell, and melanoma. Basal cell and squamous cell cancers are the most common. Melanomas account for only 4% of all skin cancer cases, however they are more dangerous because they are far more likely to spread to other parts of the body. Melanomas are responsible for about 79% of skin cancer deaths.
Who Is Affected
According to the American Cancer Society, about 53,600 people in the United States will be diagnosed with melanoma this year. The number of people developing melanoma is increasing. Its incidence rate doubled between 1973 and 2002. About 7,400 people in the United States will die of melanoma this year.
Causes and Complications
Ultraviolet radiation from the sun is the main cause of skin cancer, but artificial radiation from sun lamps and tanning booths may also cause skin cancer.
If caught early, surgical removal provides a good chance of cure. However, if melanoma spreads to distant parts of the body, treatment is generally not very effective. Symptoms associated with the spread of melanoma depend on where the cancer is located. Melanoma may spread to almost all parts of the body, including the brain, lungs, liver, bone, and other organs.
This Report Covers the Following:
National Cancer Institute
American Cancer Society
Rakel, R. Conn's Current Therapy 2002 , 54th ed., St. Louis, MO: W. B. Saunders Company; 2002: 808-809.
Last reviewed February 2003 by
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