A study looking at differences in breast density between different ethnic groups

Cancer type:

Breast cancer

Status:

Results

Phase:

Other

This study looked at how breast tissue looks on the mammograms of women from different ethnic groups.

The breasts are made up of dense glandular tissue. Once a woman is past her menopause Open a glossary item , the glandular tissue is gradually replaced by fat, which is less dense. Doctors use the term ‘breast density’ to describe how breasts look on a mammogram.

Women from the Caribbean, West Africa and India have a much lower risk of breast cancer than women from the UK. When women from these low risk countries come to live in the UK, they and their children still have a lower risk of breast cancer than white British women.

In this study, researchers wanted to find out if there were differences in breast density between women from 3 ethnic groups. The aim of the study was to see if differences in breast density could help to explain why there was a difference in breast cancer risk between the groups.

Summary of results

The researchers found that breast density was lowest in South Asian women and highest in white women.

The study included 645 women who were between 50 and 64 years old. It was carried out at a breast screening service in London.

The researchers gathered information about the women’s breast cancer risk factors from questionnaires and telephone interviews. They found that both South Asian and Afro-Caribbean women had more factors that help to protect against breast cancer including

Starting their periods later
Being shorter in height
Having more children
Having their first child at an earlier age
Being less likely to use HRT
Being more likely to breast feed their children

These factors can all offer some protection against breast cancer, but not enough to completely explain the lower rates of breast cancer in these 2 groups.

By studying the women’s mammograms, the researchers could see that both Afro-Caribbean women and South Asian women also had less dense breasts.

They suggest that the protective factors listed above can account for some of the difference in density, but not all of it. Other factors, such as diet and genetics may also have an effect. The researchers suggest that this should be studied more.

We have based this summary on information from the team who ran the study. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item ) and published in a medical journal. The figures we quote above were provided by the study team. We have not analysed the data ourselves.