Melanoma is the most serious form of skin cancer. In 2010 in the United States, it is estimated that approximately 68,100 people will be diagnosed with melanoma, and that 8,700 people will die of the disease.
It's important to know that melanoma only has its most serious consequences if it goes undiagnosed. It's fairly easy to recognize and is highly treatable if caught early.
Some risk factors for developing melanoma include:
- excessive exposure to the sun and ultraviolet (UV) radiation
- history of blistering burns (especially during childhood)
- presence of atypical moles
- having a large number of moles (i.e., more than 50 moles)
- light skin complexion (often blond or red hair and green, blue, or gray eyes)
- skin that tends to freckle or burn easily rather than tan
- personal or family history of skin cancer
- people with a weakened immune system
- taking medications that increase the skin's sensitivity to UV light
Cancer is caused by mutations of the genetic material (DNA) in a cell. The mutated genes tell the cell to divide and keep dividing, eventually producing an uncontrolled growth of cells with the same mutation. We don't understand the process fully, but we know of many carcinogens, substances that provoke or increase your chance of getting cancer.
For skin cancer, the primary carcinogen is sunlight. Studies have shown that melanoma is more common among people who have spent a lot of time in the sun. The damage caused by UV light can lead to mutations. The incidence of melanoma is rising, a reflection of the boom in sunbathing since the Second World War.
People of African descent are less likely to get melanoma than Caucasians, though they can get a rare form that appears on mucus membranes (e.g., on the inside of the mouth). Among Caucasians, paler people are more susceptible. The risk goes up with for those with blue or green eyes, fair hair, and freckles.
Most people get the bulk of their sun exposure as children, and people who had severe sunburn before age 18 are at higher risk for skin cancer. As well as UV light from the sun or indoor tanning beds, X-rays have been associated with an increased risk for melanoma, as have exposure to radium or arsenic.
Skin cells called melanocytes provide the brown pigment that results when we tan in the sun. Melanoma always starts in melanocytes. It can take root in existing moles on the skin, which are actually groups of melanocytes or it can start in a single melanocyte cell in normal skin.
Some moles are more risky than others. Dysplastic nevi are moles that look abnormal in some way and may turn into melanoma in the future. The way to recognize dysplastic nevi is as simple as ABCDE - they will have one or more of the following characteristics:
- Asymmetry: The mole is not round like normal moles, but is oddly-shaped or elongated.
- Border: The border is irregular, like a rugged coastline on a map, and the edges fade into the skin rather than making a sharp edge.
- Color: The mole has areas of different color, possibly including white, blue, red, or (especially) black.
- Diameter: It is larger than the size of a pencil eraser (or greater than 6 mm).
- Elevation: It is raised above the surface of the skin.