Researchers in this study wanted to better understand how normal breast tissue changes over a woman’s lifetime and how these changes may relate to breast cancer risk. While most breast cancer research focuses on tumor tissue, this team studied healthy breast tissue to learn what “normal” looks like and how common life factors shape breast structure over time.
The researchers analyzed breast tissue donated by over 4,100 healthy women through the Susan G. Komen Tissue Bank. Using advanced computer-based machine learning, they measured how much of the breast was made up of different tissue types, including milk-producing cells, supportive tissue, and fat. They also examined the balance between epithelial cells and stromal tissue, since disruptions in this balance may influence future cancer development.
They found that breast tissue composition shifts naturally with age, menopause, pregnancy history, breastfeeding, body weight, and family history of breast cancer. These results suggest that the normal breast environment is not static—it changes across the lifespan in ways that may help explain differences in breast cancer susceptibility among women.
