Epidemiologic studies have long linked nevi with the risk of melanoma, but until now, few clinical studies have included enough patients with complete counts of all types of moles to assess how much risk small, large, or dysplastic moles confer on a person.

The authors of this new report, eight researchers from the National Cancer Institute, the University of Pennsylvania School of Medicine, and the University of California, San Francisco, evaluated 716 patients with newly diagnosed melanomas and a control group of 1014 people who did not have melanoma. All study subjects underwent an interview (which included a history of sun exposure, the patient's occupation, residence, personal medical history, and family history of melanoma and other cancers), a complete skin examination (all moles larger than 2 mm were counted), photography of the most atypical moles, and possibly, a biopsy. The information from the melanoma patients was then compared with the information from the control group to determine the importance of moles in developing melanoma.

The moles that were evaluated ranged from normal moles to flat ones with irregular borders and color, called dysplastic nevi. Nevus is the medical term for mole; multiple moles are referred to as nevi. The research, reported in the May 14 issue of the New England Journal of Medicine, showed that the risk of melanoma rose as the number and irregularity of the nevi increased. However, dysplastic nevi are such important indicators of melanoma risk that even one dysplastic nevi can double a person's risk for developing melanoma and 10 or more dysplastic nevi increases the risk to 12 times that of normal. When evaluating non-dysplastic nevi, the researchers found that individuals with no large nevi but many small nevi had a two-fold risk of melanoma. With several large non-dysplastic nevi, the risk rose to approximately four-fold. The researchers found no risk associated with congenital nevi, those a person is born with.

Comment: Information from this study will be useful in identifying people with an increased risk of developing melanoma, who would benefit from more intensive programs for prevention and early detection of this type of cancer.

Many physicians consider melanoma an epidemic. Malignant melanoma will be diagnosed in over 40,000 people this year; about 7,300 will die from it. Deaths from melanoma have climbed steeply, an increase many doctors attribute to more recreational sun exposure and, possibly, to the thinning of the ozone layer which acts as a buffer between the earth and the sun's rays.

However, melanoma is largely preventable. The American Cancer Society encourages people to limit their sun exposure between the hours of 10:00 am and 4:00 PM, when the sun's rays are strongest, to wear sunscreen with SPF of at least 15, and to cover up with a hat, long pants and long sleeves when in the sun. Additionally, the Society notes the importance of protecting young children from the sun, since sun damage is cumulative and a bad burn in childhood can increase the risk of developing skin cancer in the future.

Give yourself and your children a skin exam from head to toe, regularly. You should be concerned about a mole if it changes suddenly or continuously or has the American Cancer Society's A,B,C,D characteristics:

• A is for asymmetry; if one half of the mole does not match the other half.
• B is for border; check for irregular, ragged, notched or blurred edges.
• C is for color; the pigmentation is not uniform with different shades of brown and black, sometimes with patches of red, white and blue.
• D is for diameter greater than 6 millimeters

For further information on skin cancer, contact the American Cancer Society at 1-800-ACS-2345.

Source: Tucker MA, Halpern A, Holly EA, et al. Clinically recognized dysplastic nevi: A central risk factor of cutaneous melanoma. JAMA, 1997:277(18)1439-1444.



Joann Schellenbach
National Director Media Relations
American Cancer Society
212-382-2169
jschelle@cancer.org