Understanding how breastfeeding reduces the risk of breast cancer

Research area: Prevention and early diagnosis

Dr James Flanagan is investigating why breastfeeding reduces the risk of developing breast cancer. His research could help to prevent more breast cancers in the future.

In this section

What's the challenge?

There are many different things that influence someone’s likelihood of developing breast cancer. And there are certain things everyone can do to lower this risk, like regular exercise, reducing alcohol intake, and not smoking.

Breastfeeding has also been linked to lower risk of developing breast cancer. But it’s not exactly clear why. If we could understand how breastfeeding might protect against breast cancer, we could better support women in making evidence-based decisions around whether to breastfeed, and how long for.

We believe that preventing breast cancer is the best way to reduce the number of women dying from the disease. To do this, we need to understand what things women could do to reduce their risk. In this study, we aim to find out why breastfeeding can lower breast cancer risk, and use this knowledge to prevent as many breast cancers as possible.

Dr James Flanagan

What's the science behind the project?

Dr James Flanagan and his team at Imperial College London previously found that breast milk sometimes has cells with potentially cancer-causing changes. Surprisingly, they only found these cells in the milk of women who had breastfed for a short time.

Now, James thinks that breastfeeding for longer periods of time removes these potentially cancer-causing cells. He and his PhD student want to test this theory.

They’re working with women taking part in the Breastmilk Epigenetics Cohort Study (BECS). Using breast milk samples donated by 300 women, the researchers are screening for cells with potentially cancer-causing changes in their DNA.

They’re also collecting samples every few months from the same women to see if changes that were detected disappear in later milk samples. This would support the idea that the longer you breastfeed, the more you are removing these cells from your body.

Lastly, the researchers will interview some of the women in the study to find out how they perceive their own risk of breast cancer, and what benefits and harms of detecting these DNA changes have.

What difference will this project make?

This project may give us new insight into why breastfeeding can reduce breast cancer risk. The study will also support women in making a more informed decision about whether they should breastfeed, and how long for.

How many people could this project help?

55,000 women are diagnosed with breast cancer every year in the UK. And this is expected to rise to 69,000 per year by 2030 if nothing is done. This research may provide women with additional knowledge of lifestyle factors which can reduce this risk.

The UK Health Security Agency reports that almost 68% of women start breastfeeding, but only 48% continue beyond 6-8 weeks in the UK.