Diabetes treatment with medicine such as metformin or with diet may reduce breast density, while taking insulin seems to increase it, according to data presented at the European Breast Cancer Conference (EBCC), underway in Amsterdam and sponsored by the European Cancer Organization (ECCO).
Dr. Zorana Jovanovic Andersen of the University of Southern Denmark in Esjberg and colleagues conducted a study that included 5,644 women who underwent mammography screening between 1993 and 2001. Of these, 4,500 were postmenopausal. More than 56% of the women had breast tissue categorized as mixed or dense; 2.4% had diabetes.
Andersen's group found that the women with diabetes were less likely to have mixed or dense breast tissue, both before and after adjusting for other factors, such as being overweight. Similar results were found in the 44 women who controlled diabetes by diet alone and the 62 who took oral medication for the condition. But those women who used insulin to control the disease had increased odds of having mixed or dense breast tissue, the researchers found.
"We know that insulin is an important growth factor for all body tissues, and even if we do not know exactly how it affects the development of cancer cells, it is also highly plausible that it increases breast density," Andersen said in a statement released by the European Cancer Organization.