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Published: 30 May 2022

RCSI begins new breast density research project

By Dr Maeve Mullooly PhD MPH,
Research Fellow,
Royal College of Surgeons in Ireland, University of Medicine and Health Sciences

Breast cancer screening plays an invaluable role in the early detection of breast cancer in Ireland. With BreastCheck – the National Breast Screening Programme - women aged 50 to 69 years are invited at regular periods to have a routine mammogram. Screening takes place at mobile and static units across the country. Around 70% of eligible women choose to come for screening.

While research has helped us learn about breast cancer, as with all things in medicine, there is a still much we don’t know. Despite medicine’s best efforts, too many women continue to be diagnosed with aggressive breast cancer. When cancer is detected early, it increases people’s opportunity to have treatment when it can have the most benefit. Because of this we would like to increase our research efforts in the area of early detection of breast cancer. 

Population screening programmes play a key part in research

We are fortunate in Ireland to have an internationally accredited national breast screening programme. The population-based coverage of the programme provides an ideal framework for conducting research that can have an impact on a national level.

Our research group in the Royal College of Surgeons in Ireland (RCSI) University of Medicine and Health Sciences is interested in conducting research that supports BreastCheck as it makes evidence-based decisions about breast screening.

What is the research about?

Our research group would like to understand more about how the healthy breast is different to a cancer-effected breast. We want to learn how we can use this knowledge about the breast to improve our understanding of how breast cancer forms.

A mammogram is an X-ray of the breast; it shows the complex biological makeup of the breast. We want to learn about how a mammogram can capture knowledge about the breast biology and how this can be used to inform us about cancer development.

Specifically, we want to learn about breast density. 'Density' describes the areas of breast tissue that appear white on a mammogram. Other research has shown that higher breast density is associated with higher future breast cancer risk, but we don’t know why that is and we don’t know which women with dense breasts will develop breast cancer. We also don’t know how best to measure breast density, or how knowledge about breast density should best be used a clinical setting.

Key points about our research

  • We aim to measure breast density among women who have attended screening and try to understand what it means for breast cancer characteristics. We believe this is one way we can continue to develop knowledge that may contribute to breast screening in the future.
  • We aim to measure breast density in mammograms of women who attended BreastCheck appointments between 2008 and 2017. We want to learn about this radiological feature and compare density measures from women who were diagnosed with breast cancer through BreastCheck, with women who have not been diagnosed with cancer. 
  • We will not perform any clinical review of mammograms and we will not look for signs of cancer. 
  • We will anonymise data in this study and therefore no woman will be identified in the findings of this research. 

We hope that this study will contribute knowledge about breast density to the international research community. 

Safeguarding patient data

We have taken a patient-first approach to developing our study and aim to ensure openness and transparency about our research. Firstly, we have sought ethical approval from a national ethics body, the Royal College of Physicians in Ireland (RCPI) Ethics Committee. We have also sought approval from the Health Research Content Declaration Committee (HRCDC), which provided feedback and permission to proceed with this research. This committee was established as part of the Health Research Regulations made under the Data Protection Act, 2018 to enable scientists and doctors to conduct research for the public good.

Our patient and public representatives have their say

We have talked to patients and the public about this study, and asked if they think it is a good idea. We have asked them what they think women who participate in screening would like to know about the study, and how best to give them this information. The patients we spoke to told us they think this is a worthwhile study. They said they are happy with how we aim to carry out the research. They agreed that women should have an option to opt out of this study, and that we should let women know about it through adverts in the national press.

Please note the deadline to opt out of this study passed on 14 July 2022.

We will provide further updates on our study on

If you have questions about this study we would like to hear from you. You can contact us at

*Updated 22.7.22