Melanoma

Melanoma
Other names	Malignant melanoma
A melanoma of approximately 2.5 cm (1 in) by 1.5 cm (0.6 in)
Pronunciation	/ˌmɛləˈnoʊmə/ ⓘ
Specialty	Oncology and dermatology
Symptoms	Mole that is increasing in size, has irregular edges, change in color, itchiness, or skin breakdown.[1]
Causes	Ultraviolet light (Sun, tanning devices)[2]
Risk factors	Family history, many moles, poor immune function[1]
Diagnostic method	Tissue biopsy[1]
Differential diagnosis	Seborrheic keratosis, lentigo, blue nevus, dermatofibroma[3]
Prevention	Sunscreen, avoiding UV light[2]
Treatment	Surgery[1]
Prognosis	Five-year survival rates in US 99% (localized), 25% (disseminated)[4]
Frequency	3.1 million (2015)[5]
Deaths	59,800 (2015)[6]

Melanoma is the most dangerous type of skin cancer; it develops from the melanin-producing cells known as melanocytes.^[1] It typically occurs in the skin, but may rarely occur in the mouth, intestines, or eye (uveal melanoma).^[1][2] In women, melanomas most commonly occur on the legs; while in men, on the back.^[2] Melanoma is frequently referred to as malignant melanoma. However, the medical community stresses that there is no such thing as a 'benign melanoma' and recommends that the term 'malignant melanoma' should be avoided as redundant.^[7][8][9]

About 25% of melanomas develop from moles.^[2] Changes in a mole that can indicate melanoma include increase—especially rapid increase—in size, irregular edges, change in color, itchiness, or skin breakdown.^[1]

The primary cause of melanoma is ultraviolet light (UV) exposure in those with low levels of the skin pigment melanin.^[2][10] The UV light may be from the sun or other sources, such as tanning devices.^[2] Those with many moles, a history of affected family members, and poor immune function are at greater risk.^[1] A number of rare genetic conditions, such as xeroderma pigmentosum, also increase the risk.^[11] Diagnosis is by biopsy and analysis of any skin lesion that has signs of being potentially cancerous.^[1]

Avoiding UV light and using sunscreen in UV-bright sun conditions may prevent melanoma.^[2] Treatment typically is removal by surgery of the melanoma and the potentially affected adjacent tissue bordering the melanoma.^[1] In those with slightly larger cancers, nearby lymph nodes may be tested for spread (metastasis).^[1] Most people are cured if metastasis has not occurred.^[1] For those in whom melanoma has spread, immunotherapy, biologic therapy, radiation therapy, or chemotherapy may improve survival.^[1][12] With treatment, the five-year survival rates in the United States are 99% among those with localized disease, 65% when the disease has spread to lymph nodes, and 25% among those with distant spread.^[4] The likelihood that melanoma will reoccur or spread depends on its thickness, how fast the cells are dividing, and whether or not the overlying skin has broken down.^[2]

Melanoma is the most dangerous type of skin cancer.^[2] Globally, in 2012, it newly occurred in 232,000 people.^[2] In 2015, 3.1 million people had active disease, which resulted in 59,800 deaths.^[5][6] Australia and New Zealand have the highest rates of melanoma in the world.^[2] High rates also occur in Northern Europe and North America, while it is less common in Asia, Africa, and Latin America.^[2] In the United States, melanoma occurs about 1.6 times more often in men than women.^[13] Melanoma has become more common since the 1960s in areas mostly populated by people of European descent.^[2][11]