Moles May Be An Indicator Of Breast Cancer: Studies
June 11, 2014

Moles May Be An Indicator Of Breast Cancer: Studies

Brett Smith for - Your Universe Online

More than just a cosmetic curiosity, cutaneous nevi – also known as moles – may be an indicator of breast cancer, according to two research studies published this week in PLOS Medicine.

Each report is based on a large prospective cohort – the Nurses' Health Study in the United States, which includes nearly 75,000 female nurses followed for 24 years, and the E3N Teachers' Study Cohort in France, which includes nearly 90,000 women followed for 18 years.

In the US-based study, scientists requested study volunteers to report the amount of moles larger than 3 millimeters on their left arm at the first assessment. They saw that women with 15 or more moles were 35 percent more likely to be identified as having breast cancer than women who noted no moles. This translated to an absolute risk of establishing breast cancer of almost 8.5 percent in women with no moles and 11 percent for women with 15 or more moles. In a subgroup of women, they found postmenopausal women with six or more moles had greater blood levels of the sex hormones estrogen and testosterone than women with no moles, and that the connection between moles and breast cancer risk vanished after adjustment for hormone levels.

In the French study, study volunteers reported if they had no, a few, many, or very many moles. They saw that women with "very many" moles had a 13 percent greater breast cancer risk than women reporting no moles, even though the association was no longer considerable after considering breast cancer risk factors, especially benign breast disease or family background of breast cancer, which were themselves connected with the number of moles.

While these analyses do not indicate that moles cause breast cancer, they raise the prospect that moles are influenced by levels of sex hormones, which may be a factor in the development of breast cancer. The results do show that the amount of moles might be used as a marker of breast cancer risk, but it is uncertain if or how this data would improve risk appraisal based on proven risk factors. The consistency of the findings is limited by the inclusion of self-reported information, the researchers said. Additionally, these findings may not pertain to non-white women since these analyses included mostly white volunteers.

"Additional studies should be carried out to investigate melanocytic nevi and other cutaneous features in association with the risks of breast cancer and other estrogen-related proliferative diseases,” said epidemiologists Barbara Fuhrman and Victor Cardenas in a perspective published alongside the two studies. “It is our 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."

Another study published this week and also based on the Nurses’ Health Study II found a link between increased consumption of red meat in early adulthood and development of breast cancer.