Melanoma Causes and Risk Factors

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Am I at Risk?

Everyone is at some risk for melanoma, but increased risk depends on several factors: sun exposure, number of moles on the skin, skin type and family history (genetics).

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  • Sun Exposure

    Both UVA and UVB rays are dangerous to the skin, and can induce skin cancer, including melanoma. Blistering sunburns in early childhood increase risk, but cumulative exposure also may be a factor. People who live in locations that have more sunlight — like Florida, Hawaii, and Australia — develop more skin cancers. Avoid using a tanning booth or tanning bed, since it increases your exposure to UV rays, raising your risk of developing melanoma and other skin cancers.

  • Moles

    There are two kinds of moles: normal moles — the small brown blemishes, growths, or "beauty marks" that appear in the first few decades of life in almost everyone — and atypical moles, also known as dysplastic nevi. Atypical moles can be precursors to melanoma, and having them puts you at increased risk of melanoma. But regardless of type, the more moles you have, the greater your risk for melanoma.

  • Skin Type

    As with all skin cancers, people with fairer skin (who often have lighter hair and eye color as well) are at increased risk.  Do you know your skin type?  Click here to take our Skin Type Quiz.

  • Personal History
    Once you have had melanoma, you run an increased chance of recurrence. People who have or had basal cell carcinoma or squamous cell carcinoma are also at increased risk for developing melanoma.

  • Weakened Immune System

    Compromised immune systems as the result of chemotherapy, an organ transplant, excessive sun exposure, and diseases such as HIV/AIDS or lymphoma can increase your risk of melanoma.

Family History

Heredity plays a major role in melanoma. About one in every 10 patients diagnosed with the disease has a family member with a history of melanoma. If your mother, father, siblings or children have had a melanoma, you are in a melanoma-prone family. Each person with a first-degree relative diagnosed with melanoma has a 50 percent greater chance of developing the disease than people who do not have a family history of the disease.

  • Close Relatives Examined

    When this skin cancer is diagnosed, it is standard practice for physicians to recommend that close relatives be examined immediately for melanoma and for the presence of unusual or atypical moles. These moles are also called "dysplastic nevi."

  • Family Syndrome

    When atypical moles are found in an individual belonging to a melanoma family, the condition is known as FAMMM, standing for Familial Atypical Multiple Mole Melanoma Syndrome. People with this syndrome are at the greatest risk of developing melanoma. In contrast, a research study found that those family members who did not have atypical moles were much less likely to develop melanoma.

  • Genetic Risk Factors

    A mutation (alteration) in a recently discovered gene, BRAF, may play a part in causing melanoma. In one study, this mutated gene was found in two-thirds of the melanoma cells analyzed. BRAF is called a "switch" gene, because it turns on to allow the cells to grow and divide. Mutations in this gene can lead to uncontrolled cell growth and cancer. The discovery of BRAF was an exciting research breakthrough, and with the development of the experimental therapy PLX-4032 (a.k.a. Zelboraf) to inhibit BRAF, physicians and patients are just starting to reap some rewards. Ultimately, increasing understanding of the BRAF gene could lead to the development of new diagnostic tools as well as new and improved drug therapies.

    The mutations most commonly seen in familial melanoma occur in another gene, p53. When this gene is in its normal state, it functions as a tumor suppressor, giving damaged cells time to repair themselves without progressing to cancer. However, when the gene is altered, it becomes unable to perform this function, and cancer can result.

    A number of gene mutations in addition to p53 and BRAF have been associated with familial melanoma, notably the CDKN2A (cyclin-dependent kinase inhibitor 2A) gene. In the future, families might be screened to identify those members who are carrying a defective gene. If, as a result, they become particulary viligant in watching their moles and having regular total-body skin examinations, a melanoma will be detected at its earliest stage, when the chances of a cure are excellent. In fact, testing is now commercially available for the presence or absence of the CDKN2A gene, but the consensus of melanoma experts is that genetic testing is not yet warranted for most people and should be done only in the context of clinical trials.

  • Moles in an Active Stage

    Moles in people belonging to melanoma-prone families are subject to change at certain times of life. They may get larger or show alterations in color or elevation, so for those periods, they are described as being active. While the reasons for these changes are not fully known, there could be a hormonal component: Moles are more active at puberty and during pregnancy. Many — but not all — physicians advise high-risk individuals not to take hormonal medications, such as oral contraceptives or hormone replacement therapy.

  • Examination Scheduling

    Individuals with atypical mole syndrome can improve their chances of early detection by increasing the frequency of skin self-examination and by visiting a physician more often for a full-body skin exam. The clinician may take photographs to document whether there are new moles or changes in older ones.

  • Children: A Special Case

    Children in melanoma-prone families need special care, because familial melanoma is likely to make its appearance early in life. Even though these cancers usually do not appear until after adolescence, they may arise in much younger children who have a family history of melanoma. Most physicians, therefore, advise parents to make a point of studying a child's skin frequently from infancy on.

    Physician examination in these families should start at the age of 10 and continue on a twice-a-year basis thereafter. Particular care should be taken at puberty and during adolescence when hormonal changes activate the moles. Here is some encouraging news: Because melanoma families are on the lookout for the disease and seek professional consultation early, the survival rate for familial melanoma is even higher than that for non-familial melanomas.