Usually, moles conjure up thoughts of skin cancer, not a malignancy of the breast. But the new studies -- one completed in France, the other carried out in the United States -- suggests that the more moles a woman has, the higher her risk of breast cancer.
The U.S. study, undertaken by researchers at Indiana University and Harvard University, charted the health of 74,523 female nurses over the course of 24 years. In France, 89,902 teachers were tracked over the same time period.
In the U.S., the nurses with no moles had an 8 percent chance of being diagnosed with breast cancer, whereas those with 15 or more moles had an 11 percent chance. The French study featured similar numbers.
"These findings also suggest that a hormonal mechanism underlies the association between nevus number and breast cancer risk," the authors of the U.S. study wrote. The study was published this week in the online journal Public Library Of Science Medicine.
The authors added: "Because this study is observational, these findings are insufficient to support any changes in clinical recommendations for breast cancer screening or diagnosis."
Dr. Deanna Attai, a breast surgeon in Burbank, California, told NBC News that the studies weren't reason for alarm, even for women with a lot of moles. "I would still put more emphasis on obesity and family history," she said.