News release

From: Peter MacCallum Cancer Centre

Harnessing our body’s natural protection against cancer

A second Australian study from 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 new 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 new study offers hope that one day we may be able to induce this natural protection against breast cancer 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 specialised 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 ten years post pregnancy and found these T-cells were still present.”

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-preventative interventions that may reduce the development of breast cancer in high-risk populations who have not conceived.”

Breast cancer affects one in seven Australian women, with 56 Australians diagnosed every day.

This research was published in Nature Immunology and was a collaborative effort with the Peter Doherty Institute and was gratefully supported by the National Breast Cancer Foundation and the Peter MacCallum Cancer Foundation.

Dr Vasanthakumar and Professor Axel Kallies (Peter Doherty Institute) are supported by NHMRC fellowships. Associate Professor Kara Britt was supported by a Victorian Cancer Agency Fellowship.