Does breast density change as a woman ages?

What do we know?
Women with higher amounts of breast density for their age are at increased risk of breast cancer and increased risk of having a breast cancer go undetected – but did you know that breast density decreases with age?
Factors that can influence changes in breast density include:

• Age
• Number of children
• Menopause
• Hormone replacement therapy (combined estrogen and progesterone has been shown to increase breast density)
• Tamoxifen.

 

What did the research ask?
Recently published research, by Jiang and colleagues from Washington University in St. Louis sought to understand the links between changes in breast density over time and breast cancer risk. The key questions asked were:

1. Does breast density change over time differently for women who later develop breast cancer?
2. Is there value in assessing breast density in each breast, rather than averaging across both breasts?
3. Can change in breast density be used to help identify women at increased risk of breast cancer to improve early detection via personalised screening recommendations?

 

How was the research done?
Women not diagnosed with breast cancer at the time of routine mammographic screening at the Joanne Knight Breast Health Centre in Missouri were invited to be part of the research.
From this group, 289 women were later diagnosed with breast cancer during the 10 years of follow-up. They were matched, based on known cancer risk factors, with 658 women who remained cancer free (the control group).
Breast density was recorded for each breast individually, rather than the average of both breasts.

 

What did the research find?
The key finding is that the women who were diagnosed with breast cancer had higher breast density at the start of the research AND a slower rate of decline in breast density in the breast that developed cancer, compared with both the unaffected breast and the women who did not develop breast cancer.

 

What does it mean for women with dense breasts?
The results of this research indicate the benefits of monitoring change in breast density in each breast as women age via routine screening mammograms.

There is also potential for measures of breast density change to be used in risk assessment models which could lead to more personalised breast cancer screening.

It is also a timely reminder for all women to be “breast aware” – aware of how their breasts normally look and feel, and report any new or unusual changes promptly to their GP. It is also important for women to attend routine mammographic screening (every two years) through BreastScreen which is free for all women aged 40 years and over.

 

Reference: Longitudinal Analysis of Change in Mammographic Density in Each Breast and its Association with Breast Cancer Risk Jiang et al JAMA Oncology 2023; 9 6: 808-814 published online April 27, 2023