Melanoma, also known as malignant melanoma, is a type of cancer that develops from cells that contain pigments known as melanocytes. Melanomas usually appear on the skin, but they rarely occur in the mouth, intestines, or eyes. In women, they most commonly occur on the legs, while in men they are more common on the back. Sometimes develop from a mole with disturbing changes include an increase in size, irregular edges, change of color, or itching skin breakdown.
The main cause of melanoma is exposure to ultraviolet (UV) light in people with low levels of pigment in the skin.
Ultraviolet light can be from the sun or from other sources, such as tanning devices. About 25% develop from moles. Those with many moles, a history of affected relatives, and who have poor immune function are at higher risk. Several rare genetic defects, such as xeroderma pigmentosum, also increase the risk. Diagnosis is by biopsy of any worrying skin lesion.
Wearing sunscreen and avoiding ultraviolet light can prevent melanoma. Treatment is usually surgical removal. In those with slightly larger cancers, nearby lymph nodes can be tested for spread. Most people are cured if it has not spread. For those in whom melanoma has spread, immunotherapy, biological therapy, radiation therapy, or chemotherapy can improvesurvival. With treatment, the five-year survival rates in the United States are 98% among those with localized disease and 17% among those in whom it has spread. How likely it is to come back or spread depends on how thick the melanoma is, how fast the cells are dividing, and whether or not the overlying skin has broken.
Melanoma is the most dangerous type of skin cancer. A level worldwide in 2012 occurred recently in 232,000 people. In 2015 there were 3.1 million with active disease that resulted in 59,800 deaths. Australia and New Zealand have the highest rates of melanoma in the world. There are also high rates in Northern Europe and North America, while it is less common in Asia, Africa, and Latin America. Melanoma is more common in men than women. Melanoma has become more common since the 1960s in areas that are mostly populated by white people.
