Researchers in this study wanted to understand how sex hormone levels influence normal breast tissue aging. They focused on a process called terminal duct lobular unit (TDLU) involution, which occurs when the milk-producing structures of the breast gradually shrink and decrease in number over time. Because less TDLU involution has been linked to a higher risk of breast cancer, researchers wanted to determine whether circulating hormone levels play a role in this process.
To investigate this, the researchers analyzed normal breast tissue samples and blood samples from healthy women. They measured levels of several hormones, including estrogen, progesterone, testosterone, and prolactin, and compared these levels with the degree of TDLU involution observed in breast tissue.
The researchers found that women with higher levels of certain sex hormones tended to have less TDLU involution, meaning more glandular breast structures remained. In particular, hormones associated with breast development and reproductive function were linked to greater numbers of TDLUs and acini. These findings suggest that hormone exposure may influence how quickly breast tissue ages and remodels throughout life.
Overall, the study provides evidence that circulating hormones play an important role in shaping normal breast tissue structure and may contribute to differences in breast cancer risk.
