Not all patients are equal when it comes to melanoma risk.
Knowing which patients may be more likely to develop melanoma can serve as a prompt to increase suspicion during examination, said Dr. James M. Grichnik. Be on the lookout for patients with the following features and characteristics, he suggested at the annual Hawaii Dermatology Seminar sponsored by Skin Disease Education Foundation.
Nevi
The presence of even one atypical (dysplastic) nevus independently predicts up to a 60% greater risk for melanoma, said Dr. Grichnik, director of the melanoma program and professor of dermatology at the University of Miami.
Higher numbers of common nevi also increase risk. Nevi counts are associated with UV exposure, and can be used as a surrogate marker for UV-induced cutaneous damage. Melanoma risk increases 47% with 16-40 common nevi on the whole body, he noted. Risk increases as mole count climbs, with nearly a seven-fold increased risk associated with nevi counts of 101 and higher (Euro. J. Ca. 2005;41:28-44).
Phenotype
Light-colored skin, hair, and eyes are associated with an increased melanoma risk. In 60 studies published before Sept. 2002, melanoma risk was twice as high with skin type I, compared with skin type IV; with fair skin color, compared with dark skin color; and with a high density rather than a low density of freckles. Compared with dark eyes, blue eyes were associated with a 47% higher risk. And melanoma risk was more than three times higher with red hair, compared with dark hair (Euro. J. Ca. 2005;41:28-44).
UV Exposure
Use of tanning beds increases melanoma risk 75% if the first exposure occurs before age 35 years, according to Dr. Grichnik. Multiple studies report that melanoma risk is higher in people who have experienced short, intense episodes of burning sun exposure (especially during childhood). The effects of chronic sun exposure are more difficult to determine, but may be associated with lentigo maligna-type melanoma.
Occupation
Airline crews, especially pilots, have a higher-than expected incidence of melanoma (BMJ 2002;325:567). This may be due to greater sun-exposed activities between flights in areas of the world with high sun exposure levels, he speculated.
Socioeconomics
Wealthier people are more likely to develop melanoma, compared with age-matched populations - the opposite of trends for squamous cell carcinoma, according to studies. Again, the higher risk for melanoma may be associated with sunny holidays in winter, and sun-exposed recreational activities enabled by affluence, Dr. Grichnik suggested.
History
Taking a good personal history can identify some of the risk factors listed above. Family history is important too - a significant proportion of patients with melanoma will have genetic risk factors for the disease, he said.
Thirteen percent of melanoma patients have at least one first-degree relative with melanoma (Hum. Genet. 2009;126:499-510). The disease appears to be twice as common in people who have a parent with a history of melanoma, three times as common if a sibling has had melanoma, and nine times as common if both a parent and a sibling have had melanoma, compared with people who have no family history of melanoma.
Once a melanoma is identifed, a variety of tools can help discern whether it is deadly, Dr. Grichnik added. These include the American Joint Committee on Cancer criteria for staging and classification of melanomas, the mitotic rate, nodal status, circulating tumor cell status, molecular marker status, and a history of prior nonmelanoma skin cancer or other cancers.
Dr. Grichnik is a founder and shareholder in DigitalDerm Inc. and has been a consultant and researcher for Electro-Optical Systems Inc. and Spectral Image Inc. SDEF and this news organization are owned by Elsevier.
Young girl having sun cream administered to her shoulder by her mother.
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