BOSTON, March 2 (UPI) -- While the people with more moles are thought to be at greater risk for melanoma, a new study shows most melanoma patients have fewer moles.
Researchers found in a study of melanoma patients that many had 20 or fewer moles, and that people with irregular moles have a much greater risk of diagnosis with aggressive melanoma.
People with 50 or more moles were found to be a lower risk of cancer and often had fewer thick or irregular moles, researchers reported.
Previous research has shown higher mole counts could increase the risk for cancer diagnosis.
Researchers in the new study suggest higher mole counts reduce the risk because of greater surveillance based on the previous studies, and making it more likely that some cancerous moles could be missed because nobody is looking for them.
For the study, researchers surveyed 566 patients within three months of a melanoma diagnosis at two academic clinics and a Veterans Affairs medical center between 2006 and 2009. The researchers categorized patients as having zero to 20 moles, 20 to 50, or 50 or more for total nevi, or moles, and subcatorized them based on having zero, one to five, or more than five atypical nevi. Tumor thickness among patients also was categorized as 2.0 millimeters or less, or 2.01 millimeters or greater.
Among the participants, 66.4 percent had zero to 20 total moles, 20.5 percent had 20 to 50 and 13.1 percent of patients had more than 50, while nearly three-quarters of patients, 73.3 percent, had no atypical moles, 14.5 percent had one to five and 12.2 percent had more than five.
In patients younger than 60, having more than 50 moles had a significantly lower risk of thick melanoma. The presence of more than five atypical moles, as compared to none, was associated with thicker melanoma, as well.
"Several novel public health messages emerge from our study, including that melanomas are more commonly diagnosed in individuals with fewer nevi compared with those with a high mole count," researchers wrote in the study, which is published in JAMA Dermatology. "Therefore, physicians and patients should not rely on the total nevus count as a sole reason to perform skin examinations or to determine a patient's at-risk status."
The study is