There’s another reason to keep an eye on your moles. Two new studies suggest that women with more moles may have a higher risk of breast cancer.
Moles are already linked with a higher risk of melanoma — the deadliest form of skin cancer. The two new studies cannot explain how moles might be related to breast cancer, but there’s a lot of research showing that moles, like breast cancer, can be influenced by hormone levels.
Moles are formed naturally by cells in the skin, and the vast majority of moles are completely harmless. But dermatologists say it’s a good idea for people to keep an eye on their moles, and report any changes such as sudden growth itching or bleeding.
In the new studies, two teams of researchers, one in France and one in the United States, looked at large surveys of tens of thousands of women. In both, women were asked about how many moles they had, in addition to a batch of other questions. They were then followed for years to see what happened to their health.
In the U.S. study, Jiali Han and colleagues from Indiana University and Harvard University studied 74,523 female nurses who had been watched for 24 years. Those who had 15 or more moles were 35 percent more likely to be diagnosed with breast cancer than women who said they didn’t have any.
After 24 years, women with no moles had about an 8 percent chance of developing breast cancer but the women with 15 or more had an 11 percent risk.
That doesn't mean that women who have lots of moles need to worry, says Dr. Deanna Attai, a breast surgeon in Burbank, California, who was not involved in the studies.