A landmark study has created the most detailed map of breast tissue aging, revealing that menopause triggers dramatic cellular changes that may allow cancer to take hold more easily.
Researchers from the University of Cambridge and the University of British Columbia analyzed tissue from 527 women aged 15 to 86. The map tracks over 3 million cells, showing that as women age, key immune and structural cells decline, while fat cells increase and blood vessels shrink.
The most striking shift occurs around menopause, when milk-producing lobules shrink or disappear, and cancer-fighting immune cells like B-cells and active T-cells are replaced by M2 macrophages, which are linked to cancer development.
This creates a more inflammatory environment where the immune system is less able to suppress emerging cancer cells. The findings may help explain why breast cancer risk rises with age, and why most cases are diagnosed in women over 50.
The study was published in Nature Aging.