Breastfeeding may protect against breast cancer for decades
A new 2025 study in Nature suggests breastfeeding can build up a long-lasting immune defense in the breast, thanks to special CD8+ T-cells that stick around for decades.
These cells seem to lower the risk and improve outcomes for tough-to-treat triple-negative breast cancer.
Study shows link between immune cells and breastfeeding
Researchers, led by Professor Sherene Loi, looked at breast tissue from over 260 women and found those who had children had more of these protective immune cells.
Mouse experiments showed these cells could actually slow down tumor growth, but removing them erased the benefit.
Looking at data from more than 1,000 breast cancer patients, women who had breastfed had better survival rates and more immune cells in their tumors.
New insights into breastfeeding's benefits
This study gives a new immune-based reason for why breastfeeding can help prevent breast cancer, not just hormonal changes.
Each year of breastfeeding cuts lifetime breast cancer risk by about 4%.
The findings could also inspire new therapies for women who can't or choose not to breastfeed.