Melanoma is a cancer that begins in the melanocytes – the cells that produce the skin coloring or pigment known as melanin. Melanin helps protect the deeper layers of the skin from the harmful effects of the sun.
Melanoma is almost always curable when it is found in its very early stages. Although melanoma accounts for only a small percentage of skin cancer, it’s far more dangerous than other skin cancers and causes most skin cancer deaths. Melanoma will account for more than 76,600 cases of invasive skin cancer in 2013. It accounts for more than 9,000 of the 12,000-plus skin cancer deaths each year.
Although researchers have found some things that can raise a person’s risk of melanoma, it’s not yet clear exactly how these factors cause melanoma. A risk factor is anything that affects your chance of getting a disease such as cancer. And risk factors don't tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And some people who get the disease may have few or no known risk factors.
Scientists have found several risk factors that could make a person more likely to develop melanoma.
The Ultraviolet (UV) Light Exposure Connection
Ultraviolet (UV) radiation is a major risk factor for most melanomas. Sunlight is the main source of UV rays. Tanning lamps and beds are also sources of UV rays. People who get a lot of exposure to light from these sources are at greater risk for skin cancer, including melanoma. Ultraviolet radiation is divided into 3 wavelength ranges:
- UVA rays cause cells to age and can cause some damage to cells' DNA. They are linked to long-term skin damage such as wrinkles, but are also thought to play a role in some skin cancers.
- UVB rays can cause direct damage to the DNA, and are the main rays that cause sunburns. They are also thought to cause most skin cancers.
- UVC rays don’t get through our atmosphere and therefore are not present in sunlight. They do not normally cause skin cancer.
While UVA and UVB rays make up only a very small portion of the sun’s rays, they are the main cause of the damaging effects of the sun on the skin. Based on what is known today, there are no safe UV rays. The amount of UV exposure a person gets depends on the strength of the rays, the length of time the skin is exposed, and whether the skin is protected with clothing or sunscreen.
The nature of UV exposure may play a role in melanoma development. Many studies have linked the development of melanoma on the trunk (chest and back) and legs to frequent sunburns (especially in childhood). The fact that these areas are not constantly exposed to UV light may also be important. Some experts think that melanomas in these areas are different from those on the face and neck, where the sun exposure is more constant. And different from either of these are melanomas that develop on the palms of the hands, soles of the feet, under the nails, or on internal surfaces such as the mouth and vagina, where there has been little or no sun exposure.
Moles - Some moles appear during our lifetime, some are present at birth. Sometimes a mole will develop cancer. Called Nevus, most moles never become cancerous. People with a close relative that have developed melanoma and who have a large number of moles, are more likely to develop melanoma. People with these two factors should have regular consultations with their dermatologist.
Predisposition: Those with Fair Skin, Freckling, and Light Hair - The risk of melanoma is more than 10 times higher for Caucasians than for African Americans. People of European descent with red or blond hair, blue or green eyes, or fair skin that freckles or burns easily are at increased risk.
Family History - Your risk is greater if one or more parent, brother, sister, or child has had melanoma. About 10% of all people with melanoma have a family history of the disease. Shared family lifestyle of frequent sun exposure, a family tendency to have fair skin, or a combination of factors may be responsible in part. It may also be due to gene changes (mutations) that run in a family. Gene mutations have been found in anywhere from about 10% to 40% of families with a high rate of melanoma.
Personal History - If you’ve had melanoma before, you’re more likely to have it again.
Immune Suppression - People who have been treated with medicines that severely suppress the immune system, such as organ transplant patients, have an increased risk of melanoma.
Xeroderma pigmentosum - XP is a rare, inherited condition resulting from a defect in an enzyme that normally repairs damage to DNA leading to development of cancers on sun-exposed areas of their skin.
Adapted from Mayo Clinic.org, Cancer.org, The Skin Cancer Foundation at SkinCancer.org, epa.gov/sunwise/statefacts.html, AimAtMelanoma.org and Melanoma.org