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Types of Cancer > Skin Cancers > Melanoma > Overview
Melanoma: The Basics
Carolyn Vachani, MSN, RN, AOCN & Suzanne McGettigan, MSN, CRNP, AOCN
Affiliation:
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: March 10, 2008
What is a melanocyte?
A melanocyte is a normal cell found in the skin that produces melanin. Melanin is a black or dark brown pigment that is seen in the skin, hair, and parts of the eye. Melanin is transferred from the melanocytes into nearby skin and hair cells. The concentrated areas of color seen on the skin are known as moles or nevi.
What is Melanoma?
Melanoma is a type of cancer that forms from melanocytes. Melanoma is the most serious form of skin cancer. Other more common, but usually less serious, types of skin cancer include basal cell carcinoma and squamous cell carcinoma.
Of the many different types of melanoma, most are seen in the skin (this also includes nail beds, soles of the feet, and scalp), but melanoma can also occur in the eye, or on mucosal surfaces which include the anal canal, rectum, and vagina. In 2008, there will be an estimated 62,480 new cases of invasive melanoma diagnosed in the United States, accounting for 5% of all new cancer diagnoses in men and 4% of new cancer diagnoses in women. The number of new cases of melanoma has steadily increased for 30 years. The increased number of cases of melanoma being diagnosed is also associated with increased survival due to early detection.
Am I at Risk for Melanoma?
Risk factors for cutaneous melanoma, or melanoma that arises in the skin, include fair skin or complexion, a history of sunburns and/or prolonged exposure to ultraviolet light (both sun and artificial UV light), multiple moles, older age, a personal or family history of non-melanoma skin cancer and a personal or family history of melanoma.
As we age, our years of sun exposure increase, and therefore the risk of melanoma increases.
Researchers have found that the risk of melanoma is 2.24 times higher in people with a first-degree relative with the diagnosis; therefore it is important to be aware of your family history. If you have been diagnosed with melanoma, it is important to share this information with your relatives so that they can undergo appropriate screening. Certain types of moles, called dysplastic nevi, are associated with a higher incidence of melanoma. These moles are typically large (>5mm in diameter) and have uneven pigmentation and borders. A single dysplastic nevi is associated with a 2-fold increased risk, while 10 or more nevi indicate a 12- fold increased risk of developing melanoma.
People with fair skin, light eyes, or those who have a tendency to freckle or burn easily are all at higher risk. Melanoma rates are 20 times higher in Caucasians than in Blacks. The melanin in dark-skinned people has been found to have a natural sun protection factor (SPF) and can filter twice as much ultraviolet light as that of a light-skinned person. This protection, however, is not complete, and melanoma can develop in dark-skinned people. Melanoma is more commonly found on soles, palms, or nail beds in dark-skinned people.
A history of 3 or more sunburns, particularly blistering sunburns, before age 20 greatly increases risk. A history of severe sunburns in childhood and adolescence may actually double the risk of melanoma in adulthood. For many years, the tanning industry has promoted tanning salons as a safe alternative to natural sun, or a way to prevent sunburn. This is because the tanning machines were said to produce only UVA rays, without producing UVB rays, which are responsible for most sunburns. Researchers have since learned that tanning beds do produce UVB rays in varying amounts, depending on the machine. They have also learned that UVA is not as safe as once thought. Despite the fact that UVA is less likely to cause sunburn, it has many biologic effects that can cause long-term damage. As for using tanning beds to prevent sunburn on a vacation, this is also untrue. A visit to a tanning bed, followed by natural sun exposure, causes a cumulative effect on skin cells and can cause an unexpected burn. Bottom line: Tanned skin is not healthy and actually indicates that the skin has been damaged.