A team of researchers has discovered how having children and breastfeeding can help lower a woman’s long-term risk of breast cancer.
The study, led by Professor Sherene Loi from Peter MacCallum Cancer Centre, was published in the journal Nature and gives new insight into how the immune system plays a role in protecting women from the disease.
Professor Loi and her team found that women who breastfeed develop special immune cells in their breast tissue. These cells are called CD8+ T cells, and they stay in the breast for many years after childbirth. They act like local security guards, always on the lookout for abnormal cells that might grow into cancer.
This discovery helps explain why having children and breastfeeding can reduce the risk of aggressive breast cancers, like triple-negative breast cancer.
Professor Loi believes these immune cells may have evolved to protect mothers during the time after pregnancy when they are more vulnerable. But today, this immune response also gives long-term protection against breast cancer.
The researchers found that going through the full cycle of pregnancy, breastfeeding, and breast recovery leads to a buildup of these protective T cells.
In lab experiments, they showed that when cancer cells were introduced, models with this reproductive history were much better at stopping or slowing down the growth of tumors—but only if these T cells were present.
The team also looked at health data from over 1,000 breast cancer patients. They discovered that women who had breastfed had tumors with more of these protective immune cells. In some groups, these women also lived longer after their diagnosis.
It has long been known that having children reduces a woman’s risk of breast cancer. Until now, many believed this was mostly due to changes in hormones during pregnancy. But this new research shows that changes in the immune system—specifically in the breast tissue—may play a bigger role than previously thought.
Understanding this could help scientists develop new ways to prevent or treat breast cancer by boosting these protective immune cells. It might even be possible in the future to create treatments that mimic the effects of pregnancy and breastfeeding to lower cancer risk.
Breast cancer remains a major health issue. Around 58 people are diagnosed with it every day in Australia. It is the second most common cancer in the country and the most common among women. Alarmingly, the number of younger women being diagnosed is rising.
This new research offers hope. By learning how the body naturally protects itself, scientists are one step closer to finding better ways to prevent breast cancer and help women live longer, healthier lives.
If you care about breast cancer, please read studies about a major cause of deadly breast cancer, and this daily vitamin is critical to cancer prevention.
For more information about cancer, please see recent studies that new cancer treatment could reawaken the immune system, and results showing vitamin D can cut cancer death risk.
The study is published in Nature.
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