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Having children can help protect women against breast cancer, a landmark study has revealed.
Australian researchers have discovered that pregnant women naturally produce cancer-killing immune cells in their breast tissue around halfway through their pregnancy.
These cells, known as killer T-cells, can help protect women against breast cancer for up to 10 years.
Women who have not carried a child do not naturally produce these protective cells, meaning they are more likely to develop the disease.
Experts say the findings could help explain the mystery rise in breast cancer cases in under 50s, with diagnoses in women aged under-50 rising by more than a fifth since the 1990s.
The disease now affects around 8,500 women of this age every year in the UK.
Meanwhile, birth rates are at their lowest in nearly half a century – and around three million women aged 16 to 45 are likely to stay childfree, according to research.
The team – from Peter MacCallum Cancer Centre – believe the findings open the door to preventative treatment and offer hope to women who can’t or don’t want to have children.
The team said their findings open up new avenues for preventative interventions that may slash the risk of cancer in high-risk women who have not conceived
‘Our research 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,’ Professor Kara Britt, the study’s co-lead author, said.
‘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 is now the most common cancer in the UK, with more than 59,000 new cases every year. But survival rates are high with around 77 per cent of women living with the disease for ten years or more.
The new study comes after recent research found breastfeeding to have a similar protective effect, delaying the onset of the disease by up to ten years.
‘People are reluctant to talk about it, but delayed childbearing is one of the biggest contributors to rising breast cancer rates,’ Dr Andrea DeCensi, director of medical oncology at Galliera Hospital in Italy, told the Daily Mail last month.
The current study – published in the journal Nature Immunology – found that pregnancy hormones trigger the production of T-cells in breast tissue, around four months into pregnancy.
These cells – which rely on milk-producing breast cells to grow – remain in breast tissue for around a decade, exerting a long-term anti-tumour effect.
Using hormone treatments, researchers were able to trigger this influx of T-cells that protect against breast cancer without the need for pregnancy – offering hope to women who can’t or don’t want to have children.
Commenting on the study, Simon Vincent, chief scientific officer at Breast Cancer Now, said: ‘We know from the Breast Cancer Now Generations study that pregnancy and childbirth reduce breast cancer risk in the long term. But we don’t know why.
‘This study offers early evidence that the changes to the immune system in the breast during pregnancy may explain that long-term protection from breast cancer.
‘We now need more research to understand this more and to see if it can open the door to new ways to prevent breast cancer.’
