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Thursday, May 23, 2013
Skin cancer exists in different types, body sites, and people. The three most common forms of skin cancer are squamous cell carcinoma, basal cell carcinoma and melanoma. Melanoma is the deadliest form of skin cancer. It occurs when the cells responsible for the skin's color (melanocytes) begin to grow and divide abnormally. 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. In most cases, melanocytes will continue to produce melanin after becoming cancerous; thus melanoma is often recognized as dark brown or black (pigmented) lesions on the skin.
Melanoma is aggressive, meaning that though the cancer may start on the skin, it can quickly spread to other parts of the body. Because melanoma spreads rapidly, it is often not discovered until it has reached its later stages when most treatments are ineffective. One person dies from melanoma every hour, and it is the most common form of cancer to be found in young adults between the ages of 25 and 29. Melanoma rates are increasing in people with each passing year, especially in young women.
Exposure to ultraviolet (UV) light has long been considered a risk factor for developing melanoma. Exposure to UV light is cumulative, meaning that our bodies accumulate more and more UV light as we age, which increases our risk for developing all three types of skin cancer. This exposure can occur in a variety of ways, including from the sun's rays and man-made sources such as tanning beds. In fact, people who use indoor tanning beds are 74 percent more likely to develop melanoma than those who have never used a tanning bed. Melanoma is often found on areas of the body that have been exposed to UV light.
However, there are exceptions to this rule. Melanoma has been known to develop on areas that have not received a great deal of UV light, such as between the toes and under folds of skin. Another important exception among this kind of skin cancer is color. While melanoma usually becomes visible as dark brown or black moles, it has also been known to be pink or light red in color. A further difference lies in who develops it. If the accumulation of UV light is the chief risk factor for melanoma, how does this explain melanoma in a ten year old boy? Why does melanoma appear in areas that are rarely exposed to the sun? Why does melanoma appear as a black mole in one person and as a pink bump in another? The answer may lie in the genetic differences that can be shared and inherited among family members as well as genetic and molecular changes within the melanomas themselves that initiate/lead to their growth.
Similar to the broader category of skin cancer, there are actually different types of melanoma. Physicians and researchers have recognized this fact by examining cancerous skin cells under a microscope; however, it is only recently that these differences in melanoma are being investigated and new treatments are being developed to "target" specific types of melanoma. Realizing what genes and molecular changes are linked to skin cancer development will allow physicians to develop treatments to address it most effectively.
This article is a NetWellness exclusive.
Last Reviewed: Jun 17, 2011
Meg R Gerstenblith, MD
Assistant Professor of Dermatology
School of Medicine
Case Western Reserve University