Findings may prompt further research
In separate studies, researchers in France and the United States have found that the more moles a woman has, the greater her risk of breast cancer.
In the U.S. study, led by Mingfeng Zhang, M.D., of Brigham and Women’s Hospital, Boston, and Jiali Han, Ph.D., of Indiana University
Simon Cancer Center, Indianapolis, investigators found that women who had 15 or more moles on a single arm were 35 percent more likely to develop breast cancer than women who had no moles.
A theory regarding the correlation is that estrogen is the common denominator of moles and breast cancer. Estrogen is known to fuel the growth and spread of many breast tumors, and is thought to influence mole growth as well.
In the study, researchers analyzed data on more than 74,500 female nurses who participated in a long-term research project called the Nurses’ Health Study that began in 1986 when the women were ages 40 to 65. Participants were asked to keep track of the number of moles on their left arm.
Over the next 24 years, nearly 5,500 of the women were diagnosed with breast cancer. More than 8 percent of the women with no moles developed breast cancer, while 10 percent of those with one to 14 moles did. Among women with 15 or more moles, 11.4 percent were diagnosed with breast cancer.
In the study overall, women with the most moles were 35 percent more likely to develop breast cancer than those with none.