Researchers in Melbourne, Australia, have made a groundbreaking discovery on how breastfeeding reshapes the immune system, providing long-term protection against breast cancer, particularly the aggressive triple-negative types.
This significant finding sheds new light on the protective effect of childbearing and its lasting impact on a woman’s immune system.
The study, published in Nature, provides a biological explanation for the protective effect of childbearing, showing how this has a lasting impact on the immune system of a woman.
According to Australia’s Peter Mac Cancer Centre (Peter Mac) in a statement released on Tuesday, which led the study, “We found that women who have breastfed have more specialised immune cells, called CD8⁺ T cells, that ‘live’ in the breast tissue for decades after childbirth,” said Prof. Sherene Loi, who is the study lead author at Peter Mac.
“These cells act like local guards, ready to attack abnormal cells that might turn into cancer,” she said.
Loi added that this protection likely evolved to defend mothers during the vulnerable post-pregnancy period, and now also lowers breast cancer risk, especially aggressive triple-negative breast cancer.
Completing a full cycle of pregnancy, breastfeeding, and breast recovery caused these T cells to accumulate in the breast, Loi said, adding their protective effect was confirmed in preclinical experiments.
“When breast cancer cells were introduced, the models with this reproductive history were far better at slowing or stopping tumour growth but only if T cells were present,” she said.
Data from over 1,000 breast cancer patients also indicated that women who breastfed had tumours with higher numbers of these protective T cells and better survival rates after diagnosis, researchers said.
Although it was once thought that pregnancy-related hormonal changes were a significant factor, childbearing lowers breast cancer risk.
This research, which points to immune changes within the breast tissue as the key factor in lowering breast cancer risk, suggests a promising future for breast cancer prevention and treatment.
The findings could pave the way for entirely new strategies in the fight against breast cancer.
As the second most diagnosed cancer in Australia, breast cancer is a pressing health issue, particularly among women, with around 58 diagnoses daily in the country.
This underscores the importance of understanding and addressing the risk factors associated with the disease.
It is a rising incidence in younger women, said the Peter Mac statement.