Breastfeeding and Breast Cancer Protection Explained

Breastfeeding may lower a woman’s risk of breast cancer, new research shows. When women nurse, their bodies create special immune cells in the breast that can detect and fight abnormal cells.

Professor Sherene Loi, who led the study at Australia’s Peter MacCallum Cancer Centre, said, “Women who have breastfed have more specialized immune cells, called CD8⁺ T cells, that ‘live’ in the breast tissue for decades after childbirth.” These cells act like guards, helping protect the breast even long after nursing ends.

The study explains that the breast changes before and after nursing through a process called involution. This natural remodeling triggers the production of these protective immune cells.

Researchers studied 1,000 women with triple-negative breast cancer, one of the most aggressive types. They found that women who breastfed had better outcomes, and their tumors had more of these protective T cells than those who didn’t nurse.

“These cells act like local guards, ready to attack abnormal cells that might turn into cancer,” Loi said. “This protection may have evolved to defend mothers after pregnancy, but today it also lowers breast cancer risk.”

It is important to note that while breastfeeding is beneficial for both mothers and babies, not every mother can produce milk, a condition known as hypolactation.