Arm Mole Count Can Accurately Predict Skin Cancer Risk

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Sun exposure is the leading cause of skin cancer. A new study has found that those with over 11 moles on their right arm have a higher-than-average chance of skin cancer. Dani Cardona/Reuters

People with more than 11 moles on their right arm have a higher-than-average risk of developing skin cancer, according to research published in the British Journal of Dermatology on Monday.

Researchers from King's College London found that counting the number of moles on someone's right arm can be used to accurately estimate how many moles the person has on their body in total. They studied data from 3,595 female twins, and found that those with more than seven moles on their right arm were nine times more likely to have 50 on their whole body as compared to the average woman. And those those with more than 11 were likely to have more than 100, which the researchers say is an indication of significant melanoma risk.

Melanoma is a skin cancer that results from irregular moles; the American Cancer Society predicts that there will be 73,000 new cases of melanoma diagnosed in 2015.

"The findings could have a significant impact for primary care, allowing GPs to more accurately estimate the total number of moles in a patient extremely quickly via an easily accessible body part," Simone Ribero of the Department of Twin Research & Genetic Epidemiology, and lead author of the recent study, said in a press release. "This would mean that more patients at risk of melanoma can be identified and monitored."

According to Cancer Research U.K., other risk factors for melanoma include having red or fair hair, fair skin, light-colored eyes or having been sunburnt in the past.

Dr. Claire Knight, health information manager at Cancer Research U.K., praised the research but warned that "less than half of melanomas develop from existing moles. So it's important to know what's normal for your skin and to tell your doctor about any change in the size, shape, color or feel of a mole or a normal patch of skin. And don't just look at your arms—melanoma can develop anywhere on the body, and is most common on the trunk in men and the legs in women."