Pregnancy recruits killer T cells that may guard breasts against cancer for years
· Medical Xpressby Peter MacCallum Cancer Centre
edited by Sadie Harley, reviewed by Andrew Zinin
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An Australian study by researchers at Peter Mac has shown that the natural protection against breast cancer offered by childbearing is due to the influx of killer T cells to the breast. The research shows that the cells begin to populate the breast during pregnancy and are closely linked to the changes in the breast epithelial cells.
The research was published in Nature Immunology and was a collaborative effort with the Peter Doherty Institute.
Long-lived cells in the breast
The study offers hope that one day this natural protection against breast cancer could be induced without the need to conceive, offering hope to women who can't or have chosen not to have children. Co-lead researcher, Associate Professor Kara Britt, said that until now, the mechanisms that linked childbirth to breast cancer protection were only partially understood.
"Our research deepens our understanding and shows that women had better outcomes if they have breast tissue with high levels of killer T cells—a specialized immune cell that helps detect and destroy abnormal cells like cancer," she said.
"We uncovered that the tissue-resident memory T cells are recruited during pregnancy, but survive for a long time and potentially stay in the breast tissue, patrolling it for abnormal cells for years.
"We examined breast tissue 10 years post-pregnancy and found these T cells were still present."
Hormone treatment mimicked pregnancy changes
Peter Mac study co-lead Dr. Ajithkumar Vasanthakumar further explained that these tissue-resident memory-like cells start to take up residency halfway through pregnancy and remain well after breastfeeding.
"Our research suggested that the tissue-resident T cells rely on the milk-producing breast cells for survival and growth and were embedded within the milk ducts," he said.
"Employing experimental models, we used hormone treatments to bring about the same changes in the breast cells to induce tissue-resident memory T cells that protect against breast cancer, without the need for pregnancy.
"These findings are very exciting and open up new avenues for immune-preventive interventions that may reduce the development of breast cancer in high-risk populations who have not conceived."
Publication details
Tabinda Hussain et al, Pregnancy-induced tissue-resident memory-like T cells contribute to tumor control in breast cancer, Nature Immunology (2026). DOI: 10.1038/s41590-026-02579-3
Journal information: Nature Immunology
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OncologyWomen's healthAllergy and immunologyObstetrics & gynecologyPregnancyCommon illnesses & Prevention Provided by Peter MacCallum Cancer Centre Who's behind this story?
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