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Melanoma is the most dangerous type of skin cancer. It is the leading cause of death from skin disease.
Melanoma can also involve the colored part of the eye.
Skin cancer - melanoma
Causes, incidence, and risk factors
Melanoma is caused by changes in cells called melanocytes, which produce a skin pigment called melanin. Melanin is responsible for skin and hair color. It can appear on normal skin, or it may begin as a mole or other area that has changed in appearance. Some moles that are present at birth may develop into melanomas.
There are four major types of melanoma:
- Superficial spreading melanoma is the most common type. It is usually flat and irregular in shape and color, with different shades of black and brown. It is most common in Caucasians.
- Nodular melanoma usually starts as a raised area that is dark blackish-blue or bluish-red. However, some do not have any color.
- Lentigo maligna melanoma usually occurs in the elderly. It is most common in sun-damaged skin on the face, neck, and arms. The abnormal skin areas are usually large, flat, and tan with areas of brown.
- Acral lentiginous melanoma is the least common form. It usually occurs on the palms, soles, or under the nails and is more common in African Americans.
Rarely, melanomas appear in the mouth, iris of the eye, or retina at the back of the eye. They may be found during dental or eye examinations. Although very rare, melanoma can also develop in the vagina, esophagus, anus, urinary tract, and small intestine.
Melanoma is not as common as other types of skin cancer. However, the rate of melanoma is steadily increasing.
The risk of developing melanoma increases with age. However, it is also frequently seen in young people.
You are more likely to develop melanoma if you:
- Have fair skin, blue or green eyes, or red or blond hair
- Live in sunny climates or at high altitudes
- Spent a lot of time in high levels of strong sunlight, because of a job or other activities
- Have had one or more blistering sunburns during childhood
- Use tanning devices
Other risk factors include:
- Close relatives with a history of melanoma
- Certain types of moles (atypical or dysplastic) or multiple birthmarks
- Weakened immune system due to disease or medication
A mole, sore, lump, or growth on the skin can be a sign of melanoma or other skin cancer. A sore or growth that bleeds, or changes in skin coloring may also be a sign of skin cancer.
The ABCDE system can help you remember possible symptoms of melanoma:
Asymmetry: One half of the abnormal area is different from the other half.
Borders: The edges of the growth are irregular.
Color: Color changes from one area to another, with shades of tan, brown, or black, and sometimes white, red, or blue. A mixture of colors may appear within one sore.
Diameter: The spot is usually (but not always) larger than 6 mm in diameter -- about the size of a pencil eraser.
Evolution: The mole keeps changing appearance.
The key to successfully treating melanoma is recognizing symptoms early. You might not notice a small spot if you don't look carefully. Have yearly body checks by a dermatologist, and examine your skin once a month. Use a hand mirror to check hard-to-see places. Call your doctor if you notice anything unusual.
Signs and tests
Your doctor will check your skin and look at the size, shape, color, and texture of any suspicious areas.
If your doctor thinks you might have skin cancer, a piece of skin will be removed and sent to a lab for examination under a microscope. This is called a skin biopsy. There are different types of skin biopsies. All or part of the growth will be removed.
A sentinel lymph node (SLN) biopsy may be done in some people with melanoma to see if the cancer has spread to nearby lymph nodes.
Once melanoma has been diagnosed, CT scans or other types of x-ray tests may be done to see if the cancer has spread.
Surgery is needed to treat melanoma. The skin cancer and some surrounding tissue will be removed. How much skin is removed depends on how deep the melanoma has grown.
If the cancer has spread to nearby lymph nodes, these lymph nodes may also be removed. After surgery, you may receive a medicine called interferon.
Treatment is more difficult when the melanoma has spread to other organs. When it spreads to other organs, it usually cannot be cured. Treatment involves shrinking the skin cancer and making you as comfortable as possible. You may receive:
- Chemotherapy: Medicines are used to kill cancer cells. It is usually given if the melanoma has returned or spread.
- Immunotherapy: Medications such as interferon or interleukin help your immune system fight the cancer. They may be used along with chemotherapy and surgery.
- Radiation treatments: These may be used to relieve pain or discomfort caused by cancer that has spread.
- Surgery: Surgery may be done to remove cancer that has spread to other parts of the body. This is done to relieve pain or discomfort associated with the growing cancer.
If you have melanoma that is hard to treat, you might consider enrolling in a clinical trial. Ask your doctor for more information. Researchers continue to study new treatments.
How well a patient does depends on many things, including how quickly the cancer was diagnosed and how far it has spread.
If caught early, some melanomas can be cured.
Melanoma that is very deep or has spread to the lymph nodes is more likely to return after treatment. If it is deeper than 4 mm or has spread to the lymph nodes, you are more likely to have the cancer spread to other tissues and organs.
Melanoma usually cannot be cured when the cancer has spread beyond the skin and nearby lymph nodes.
If you have had melanoma and recovered, it is very important to examine your body regularly for any unusual changes. Your risk for melanoma is increased once you have had this cancer. Melanoma may return years later.
Melanoma can spread to other parts of the body very quickly.
Melanoma treatment can cause side effects, including pain, nausea, and fatigue.
Calling your health care provider
Call your health care provider if you notice a new growth or any other changes in your skin. You should also call if an existing spot becomes painful or swollen, or if it starts to bleed or itch.
The American Cancer Society recommends professional skin examinations every year for people older than 40, and every 3 years for people ages 20 - 40.
You should also examine your skin once a month, using a mirror to check hard-to-see places. Call your doctor if you notice any changes.
The best way to prevent skin cancer is to reduce your exposure to sunlight. Ultraviolet light is most intense between 10 a.m. and 4 p.m., so try to avoid sun exposure during these hours. Protect the skin by wearing hats, long-sleeved shirts, long skirts, or pants.
Apply high-quality sunscreens with sun protection factor (SPF) ratings of at least 15, even when you are only going outdoors for a short time.
Apply a large amount of sunscreen on all exposed areas, including ears and feet.
Look for sunscreens that block both UVA and UVB light.
Use a waterproof formula.
Apply sunscreen at least 30 minutes before going outside, and reapply it frequently, especially after swimming.
Use sunscreen in winter, too. Protect yourself even on cloudy days.
Other important facts to help you avoid too much sun exposure:
- Avoid surfaces that reflect light more, such as water, sand, concrete, and white-painted areas.
The dangers are greater closer to the start of summer.
Skin burns faster at higher altitudes.
Avoid sun lamps, tanning beds, and tanning salons.
Goodson AG, Grossman D. Strategies for early melanoma detection: Approaches to the patient with nevi. J Am Acad Dermatol. 2009;60:719-735.
Hodi FS, O'Day SJ, McDermott DF, et al. Improved survival with ipilimumab in patients with metastatic melanoma. N Eng J Med. 2010;363:711-723.
Lange JR, Fecher LA, Sharfman WH, et al. Melanoma. In: Abeloff MD, Armitage JO, Nierderhuber JE, Kastan MB, McKenna WG, eds. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa: Churchill Livingstone; 2008:chap 73.
National Comprehensive Cancer Network. NCCN Medical Practice Guidelines and Oncology: Melanoma. V.4.2011.
- Last reviewed on 5/4/2012
- A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network (7/26/2011).
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