Moles Associated with Breast Cancer: Studies

Moles or cutaneous nevi might serve as a predictor for breast cancer, two new studies suggest.

According to Jiali Han and colleagues from Indiana and Harvard University, women with many moles have a higher risk of developing breast cancer. There is no need to panic because researchers haven't found a cause and effect relationship.

The first study was based on data from the Nurses' Health Study in the United States, which included more than 74,523 female nurses while the second one used data from E3N Teachers' Study Cohort in France, including 89,902. The women in the U.S. were followed for 24 years while those in France for 18 years, according to a news release.

Researchers found that women with more than 15 nevi >3mm on the left arm had a 35 percent increased risk of breast cancer than other women. 

"Postmenopausal women with six or more nevi had a 45.5 percent higher level of free estradiol and a 47.4 percent higher level of free testosterone compared to those with no nevi," researchers wrote, nbcnews reported.

Marina Kvaskoff and colleagues from INSERM, France looked into the data from the teacher cohort. They found women with several nevi had 13 percent higher risk of breast cancer than women with no nevi.

Moles are already linked with melanoma risk, nbcnews reported, Melanoma is the deadliest type of skin cancer. Moles pose no health risks, but experts warn that people keep an eye on mole growth as sudden change in appearance of moles could mean health complications such as cancers.

The studies don't show any cause and effect relationship between number of moles and breast ancer, but show that the hormones Associated with mole growth might be linked with breast cancer. Moreover, the findings can't be applied to non-white people because the data was collected only from white women. The data was also self reported, which is again a limitation in this kind of research.

"It should really not panic women who have a lot of [moles] since these are very new findings. The association is very modest," said Kvaskoff, according Time. "We are noticing this link, and we hope that it will generate more knowledge. If it is confirmed with other research, it could become a risk marker for breast cancer or other hormonal conditions, but it's too soon to be associated with a breast cancer diagnosis. We hope this will generate more research."

The study is published in the journal PLOS Medicine.