London: A new study suggests that women with moles or nevi are more likely to develop breast cancer.
Jiali Han and colleagues from Indiana University and Harvard University, United States, and Marina Kvaskoff and colleagues from INSERM, France, reached to the conclusions by using data from the Nurses' Health Study in the United States, including 74,523 female nurses followed for 24 years, and the E3N Teachers' Study Cohort in France, including 89,902 women followed for 18 years.
In the first study, the researchers observed that women with 15 or more nevi were 35 percent more likely to be diagnosed with breast cancer than women who reported no nevi, corresponding to an absolute risk of developing breast cancer of 8.48 percent in women with no nevi and 11.4 percent for women with 15 or more nevi.
In the E3N study, it was found that women with "very many" nevi had a 13 percent higher breast cancer risk than women reporting no nevi, although the association was no longer significant after adjusting for known breast cancer risk factors, especially benign breast disease or family history of breast cancer, which were themselves associated with nevi number.
These studies only raise the possibility that nevi are affected by levels of sex hormones, which may be involved in the development of breast cancer. The findings do suggest that the number of nevi could be used as a marker of breast cancer risk, but it is unclear whether or how this information would improve risk estimation based on established risk factors.
Moreover, these findings may not apply to non-white women given that these studies involved mostly white participants.
In a linked Perspective, Barbara Fuhrman and Victor Cardenas said that additional studies should be carried out to investigate further and they hope that this research will provide etiologic insights and test practical uses of nevi and related phenotypes for their potential utility in breast cancer risk assessment.
The studies were published in PLOS Medicine.
