Pregnancy is one of the most fascinating functions of the human body with far-reaching effects that ripple for years. Research has long shown that childbearing can help reduce a woman’s long-term risk of breast cancer. Now, a recent study published in Nature shows that breastfeeding can have even more of an impact on the immune system and cancer prevention.
“We found that women who have breastfed have more specialized immune cells, called CD8⁺ T cells, that ‘live’ in the breast tissue for decades after childbirth,” oncologist Dr. Sherene Loi, who led the research out of Peter MacCallum Cancer Centre in Melbourne, says in the press release. “These cells act like local guards, ready to attack abnormal cells that might turn into cancer. This protection may have evolved to defend mothers during the vulnerable post-pregnancy period, but today it also lowers breast cancer risk, especially the aggressive type called triple-negative breast cancer,” she explains.
In the research, when breast cancer cells were introduced, the participants who had experienced a full cycle of pregnancy, breastfeeding and breast recovery were shown to be far better at slowing or stopping tumor growth if T cells were present, says Dr. Loi. “We also studied data from over 1,000 breast cancer patients and found women who breastfed had tumors with higher numbers of these protective T cells and, in some groups, they lived longer after diagnosis of breast cancer,” she adds.
For years, hormonal changes were thought to be the major factor in helping reduce a mother’s breast cancer risk. Now, this research suggests the added protection is actually a result of immune changes within the breast tissue.
