Melanoma is a type of skin cancer that begins in the skin's pigment-producing cells, called melanocytes. These cells make melanin, which is responsible for the color in skin, eyes and hair.
The National Cancer Institute estimates there will be 68,130 new cases of melanoma in the United States and 8,700 deaths from melanoma in 2010.
Melanoma is the deadliest form of skin cancer, but it is not the most common. Basal cell and squamous cell skin cancers occur more often than melanoma, according to the Skin Cancer Foundation.
Causes & Risk Factors
Exposure to ultra violet (UV) rays from sunlight is a leading cause behind melanoma. When sunlight hits melanocytes, they make more of the pigment melanin, darkening the skin. This can result in a tan, freckles or moles – the vast majority of which are benign.
Researchers believe that enough UV radiation exposure can damage the DNA in melanocytes, causing them to grow out of control into a tumor. Blistering sunburns in childhood, use of tanning beds and any excessive exposure to UV radiation increases the risk for melanoma, according to the Mayo Clinic.
A melanoma tumor often originates in an existing mole or starts as its own lesion that looks like a mole. People with more than 50 ordinary moles are more likely to develop melanoma, according to the National Cancer Institute.
Melanoma also strikes fair-skinned people more often. Having less pigment in your skin means you have less protection from UV radiation. Caucasians are 30 times more likely to develop invasive melanoma than people of African descent, according to the National Cancer Society.
Melanoma tumors most often occur in areas of the body that are exposed to direct sunlight such as the arms, legs, head and face, according to the Mayo Clinic. Yet, melanoma can form anywhere on the body where there is melanin, including the eyes and the small intestines, according to the National Cancer Institute.
One type of melanoma, called acral lentiginous melanoma, may appear as a black or brown discoloration on the soles of the feet, under the nails or on the palms of the hand.
Since melanoma can occur in areas of the body with little to no sun exposure, doctors believe a combination of genetic and environmental factors -- including UV exposure -- may lead to melanoma, according to the Mayo Clinic.
People with a family history of melanoma are more likely to develop the cancer. One in 10 people diagnosed with melanoma have a family member who was also diagnosed with the disease, according to the National Cancer Institute.
Symptoms & Diagnosis
The first signs of melanoma appear as an unusual mole or as changes to an existing mole.
A mole that is asymmetric in shape, has a ragged border, has uneven coloration, is larger than the diameter of a pencil eraser and has changed in appearance may be a sign of melanoma.
An easy way to remember what changes to look for in moles is to refer to your ABCs: A is for asymmetry, B is for border, C is for color, D is for diameter and E is for evolving, according to the National Institutes of Health.
A mole that bleeds or itches is also a warning sign for melanoma.
Trained dermatologists can perform head-to-toe screenings to find any irregular moles. However, the only way to diagnose melanoma is with a biopsy, according to the Mayo Clinic.
Melanoma often has good prognosis when the cancer is caught early. If the lesion has not spread beyond the surface of the skin, simple surgery may be enough to cure cancer.
The National Cancer Institute estimates people diagnosed with localized melanoma have a five-year survival rate of 98 percent. Luckily, 84 percent of melanoma cases are diagnosed at this stage.
However, if melanoma spreads to other parts of the body, it can be difficult to treat, according to the NIH.
If melanoma has spread under the skin to nearby lymph nodes, the five-year survival rate is 62 percent. If it has spread to distant parts of the body, the five-year survival rate is 16 percent.
People whose melanoma has spread beyond their skin may require chemotherapy, radiation or biological therapy to treat the cancer. In biological therapy, doctors boost an individual's immune system to fight off cancer.
Preventing melanoma can be a lifelong task, but it only takes a few simple precautions to reduce the risk.
Avoiding tanning beds is an easy step, as is wearing sunscreen year-round. The Mayo Clinic recommends wearing a sunscreen with a sun protection factor (SPF) of at least 15.
Wearing hats, visors and tightly woven clothing is also a great way to block UV rays.
Finally, staying out of the midday sun -- between 10 a.m. and 4 p.m. -- will protect skin from the sun's radiation when it is strongest.
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